CDK6 and intrahepatic cholangiocarcinoma: Interestingly, upregulation of CDK6, p-CDK2 and cyclin E1 was observed in T47D-derived-resistant cells (TPF-R) compared with the sensitive cell lines (T47D-S), and the MCF7-derived-resistant cells (MPF-R) showed also upregulation of CDK6 and p-CDK2 compared to the parental cell line (MS), as shown by ICC and western blotting (Fig. 1e, f and Supplementary Fig. 3b).