LNCaP and PC-3 cells were treated with F-4 for 24, 48, and 72 hours. Samples were mixed with equal parts Trypan Blue and assessed for viability. Percentage viability was calculated as described in Materials and Methods. Asterisk(s) *, **, *** indicates significant P value <0.05, <0.01, and <0.001, respectively, by two-tailed t-test compared to vehicle-treated control.