TKT and prostate cancer: The cell lines tested, including prostate cancer and bone stromal cell lines, revealed successful TK gene transduction by Ad-522E-TK with an at least two-fold stronger activity in AR-negative prostate cancer cells DU145, PC3 and PC3M as well as bone stromal cells MG63 and HS27A in comparison with AR-positive LNCaP lineage cell lines (Fig 3A), which was similar to the result of luciferase reporter activity by p522E-Luc (Fig 2C).