Supplementary Figure Legends Supplementary Figure 1- PLGF/VEGF induces FLT-1 accumulation in cell membrane protrusions with minor effects on leukemia cell survival. (A) PLGF and VEGF stimulation for 24 hours of leukemia cells promoted a minor increase in leukemia cell viability. These results were repeated three times and the error bars depict the standard error of the mean. (B) Leukemia cells were attached to poly-L-lysine coated slides, left untreated or stimulated with PLGF/VEGF for 15 minutes (100 ng/mL and 50 ng/mL, respectively), fixed and immuno-stained with anti-FLT-1 antibody. An FLT-1 inhibitor (IR1) was used to demonstrate the specificity of PLGF effects. Confocal analysis of FLT-1 membrane protrusions in HEL cells are indicated by white arrows (z-projections of 0.5 m optical sections). Supplementary Figure 2-- PLGF/VEGF induces co-localization of FLT-1 with polymerized actin in HEL cells. (A) Co-localization of FLT-1 (red) with polymerized actin (green) in membrane protrusions was assessed by immunofluorescence after cell stimulation with PLGF for 30 minutes. (B) After immunofluorescence staining, 6 distinct powerfields were chosen for each condition (control and PLGF stimulated cells) and the number of cells with protrusion formation of FLT-1/F-actin were counted and represented in relation to control cells. Supplementary Figure 3- PLGF stimulation promotes FLT-1:Hsp90 association to actin-cytoskeleton but not with microtubules. HEL cells were stimulated or not with PLGF and total cell extracts were prepared and immunoprecipitated with anti--tubulin antibody and analysed by SDS-Page. Blots were incubated with anti-FLT-1 and antiHsp90 antibodies. The results are representative of 3 independent experiments. Supplementary Figure 4- Caveolin binding domains in FLT-1 aminoacid sequence. Four potential caveolin-binding sites were found throughout the entire Human FLT-1 sequence (underlined and in grey) in the total protein amino acid sequence of human FLT-1 (SWISSPROT database search). Supplementary Figure 5- PLGF stimulation of AML cells induces caveolin-1 protein expression and interaction with FLT-1. (A)- Total leukaemia cell extracts were analysed by SDS-Page and after western blolt analyses an increase in caveolin-1 protein expression was detected in AML cells after PLGF stimulation. (B) Coimmunoprecipitation of caveolin-1 from HEL total extracts showed an in vitro association with the molecular chaperone Hsp90, - actin and FLT-1. Total nonimmunoprecipitated cell extracts (50 g) were used as control. The autoradiographs shown are representative of similar results from three independent experiments. Supplementary Figure 6- Actin-cytoskeleton destabilization by cytochalasin D blocks PLGF-induced leukemia cell migration. (A) Leukemia cell treatment with cytochalasin D at 50 ng/mL decreased significantly PLGF-induced leukemia cell migration (total number of cells in 5 HPF of a transwell migration system; p<0.05) and (B) cell survival (p<0.05). Results are representative of 3 independent experiments. Error bars depict the standard error of the mean. Supplementary Figure 7- Treatment with Cytochalasin D blocks cell protrusion formation and interactions of caveolin-1 with FLT-1, HSP90 and actin cytoskeleton. (A) Treament of leukemia cells with cytochalasin D for 30 minutes stopped protrusion formation in PLGF-induced cells (z-projections of 0.5 m of confocal optical sections; red- FLT-1, green- phalloidin-FITC) and (B) blocks the interaction between FLT-1, -actin, Hsp90 and caveolin-1 at the cell membrane found with immunoprecipitation assays with anti-caveolin-1 antibody. Supplementary Figure 8- Microtubular destabilization with Taxol does not affect membrane protrusion formation induced by PLGF stimulation. Leukemia cells were attached to poly-L-lysine coated slides, and were treated with taxol, a microtubulepolimerizing agent (taxol at 100 ng/mL), fixed and immuno-staining with anti-FLT-1 antibody or double-stained with mouse anti--tubulin antibody. Treatment of leukemia cells with does not stop PLGF-induced formation of membrane protusions z-projections of 0.5 m of confocal optical sections; red- FLT-1, green- -tubulin).