Clonogenic assay for LNCaP-COX-2 and LNCaP-Neo treated with irradiation. Clonogenic assay for LNCaP-COX-2 and LNCaP-Neo treated with irradiation (0, 2 or 4 Gy) with or without diclofenac (IC25). Cells were seeded in 6-well plate, and treated with or without diclofenac for 48 hours, irradiated, and allowed to form colonies. (A) Survival fractions for radiation and diclofenac were normalized by dividing by the survival fractions for untreated cells. LNCaP-COX-2 cells was more radioresistant than LNCaP-Neo cells (p = 0.0225). In LNCaP-COX-2 cells, diclofenac enhanced the effect of RT with significant differences between RT alone and RT with diclofenac, when cells were exposed to 2 Gy (p = 0.0466). (B) Clonogenic assay of LNCaP-COX-2 cells and LNCaP-Neo cells treated with RT (0, 2 or 4 Gy) and diclofenac (0 or IC25). Photographs of 6-well plates in a representative experiment are shown.