To further determine the effect of PROTAC 5 in in vitro models of prostate cancer and confirm the AKR1C3 target of action we incubated PROTAC 5 and warhead inhibitor 4 in 22Rv1 cells (moderate expression of AKR1C3), 22Rv1 cells grown in charcoal stripped serum (CSS) (high AKR1C3 expression), LNCaP cells (AKR1C3 null) and AKR1C3 stably transfected LNCaP1C3 cells (Fig. 9)7, and determined cell viability by the MTT assay. Here, AKR1C3 is linked to Familial prostate cancer.