To elucidate if crambescidins could induce cell cycle arrest and apoptotic death of tumor cells in a p53-independent manner, casapase-3 activity determination following p53 inhibition with Pifithrin α in p53 expressing cells, and effects on the p53-null PC3 prostate cancer cells viability were also assayed. This evidence concerns the gene TP53 and Familial prostate cancer.