Cell culture and senescence induction

HCT116 cells were cultured in DMEM supplemented with 10% FBS. Normal HCT116 cells were treated with 100 nM Doxorubicin for 4 days to induce senescence. IMR90 human diploid fibroblasts (HDFs) were purchased from the American Type Culture Collection (ATCC) and cultured in DMEM with 10% FBS. ER:Ras-IMR90 cells were generously provided by Masashi Narita, Cancer Research U.K., Cambridge Research Institute, and were given 100 nM 4-hydroxytamoxifen (4-OHT) to induce ER-Ras fusion protein expression and maintained in 4-OHT–containing DMEM (w/o phenol red) with 10% FBS until harvesting. Human diploid 2BS fibroblasts cells (National Institute of Biological Products, Beijing, China) were cultured in DMEM supplemented with 10% FBS.