METHODS
PSMA cell-surface expression
Cell-surface expression was determined by flow cytometry using antibodies specific to human PSMA
(MBL International, K0142-5). CT26, PC3 or 22Rv1(1.7) cells were grown in 60mm tissue culture dishes
(BD Falcon, 353002). On the day of the experiment cells were trypsinized (0.05% trypsin-EDTA), washed three times in DPBS, and counted using a hemocytometer. 2×10 5 cells/mL were counted and resuspended in 1mL of DPBS and 4% FBS and incubated for 30min at 25ºC. Cells were then pelleted and resuspended in 100μl of DPBS and 4%FBS containing 20mg/ml of primary antibody against PSMA or
20mg/ml of isotype-specific control antibody (labeled with Phycoerythrin). Then, cells were washed twice with 500μl Block, fixed in 500μL 1% formaldehyde in DPBS and analyzed by flow cytometry at the Flow Cytometry Facility (University of Iowa; http://www.healthcare.uiowa.edu/CoreFacilities/FlowCytometry/).
Docetaxel cell survival assay
PC-3 and PC-3-(PSMA ++ ) cells were serum starved by incubating cells in folate-free RPMI 1640 media lacking FBS for 24h prior to seeding. Synchronized cells were seeded at 1500 cells/well in quadruplicate in 96-well tissue culture plates (Corning Inc., 3596) and incubated for 24h at 37°C in folate-free RPMI
1640 media supplemented with 10% FBS. Medium was replaced with 100μl/well fresh medium containing serial dilutions of Docetaxel (1μM - 16pM). The relative number of viable cells in each well was then determined 48h after treatment using the Cell Titer 96 AQueous One Solution Cell Proliferation
Assay.
 -Irradiation cell survival assay
Viability of PC-3 cells (with or without PSMA expression) in response to  -irradiation was determined by clonogenic assay as previously described 48 . Briefly, PC-3 cells were plated at low density in folate-free

RPMI 1640 media in 6-well plates (Corning Inc., 3516). Cells were treated with  -radiation (0, 2, 4, 6,
8gy) from a JL Shepherd Cesium-137 irradiator (Rad Source, San Fernando, CA). Following irradiation, cells were allowed to proliferate in culture up to 2 weeks. After media was aspirated, cells were washed, fixed and stained for 1h with Crystal violet Fixing Solution (0.25% Crystal Violet, 3.7% formaldehyde,
10% H
2
O, 80% methanol). Colonies containing greater than 50 cells were counted. Plating efficiency and surviving fraction were determined as described previously 49 .
UV cell survival assay
Viability of PC-3 cells (with or without expression of PSMA) in response to UV exposure was determined using a clonogenic assay as described 50 . Briefly, PC-3 cells were plated at low density in folate-free RPMI 1640 media in 6-well plates (Corning Inc., 3516). Media was removed and cells were treated with UV-C (0, 5, 10, 15, 20, 25J/m 2 ) from a Sylvania Germicidal lamp (Danvers, MA). Following
UV exposure, cells were returned to folate-free RPMI 1640 media allowed to proliferate in culture for up to 2 weeks. Media was aspirated. Cells were washed with DPBS, fixed and stained for 1h with Crystal
Violet Fixing Solution as described above. Colonies containing greater than 50 cells were counted.
Plating efficiency and surviving fraction were determined as described previously 49 .