Reagents and cell culture

Apigenin was obtained from Sigma (St. Louis, MO, USA) and dissolved in DMSO (vehicle). Final DMSO concentrations used in vitro were ≤ 0.2%. Antibodies specific to GAPDH, p53, BAX, Cyclin B1, caspase 3 and caspase 9 were purchased from Santa-Cruz Biotechnology (Santa Cruz, CA, USA). ATM, p-ATM, γH2AX, p-Chk2, Cdc25c, p-Cdc25c (Ser216) and p-Cdc2 (Tyr15) antibodies were purchased from CST (Danvers, MA, USA) and applied according to the manufacturer's protocol.

Human RCC cell lines, ACHN, 786-0, and Caki-1, were obtained from the Shanghai Institute of Cell Biology, Chinese Academy of Sciences (Shanghai, China) and cultured in MEM, RPMI 1640, and McCOY's 5A medium (HyClone, Logan, UT, USA), respectively, supplemented with 10% heat-inactivated fetal bovine serum at 37°C in 5% CO₂.