For the time course study, cells were treated with 20 μM of EGCG for 12, 24, 48, 72, or 144 h. Human
colon cancer cell line HT - 29 and prostate cancer cell line PC3 were obtained from American Type Culture Collection (Manassas, VA), and were grown in McCoy's 5A and RPMI 1640 containing 10 % fetal bovine serum, respectively.