CCND1 and neoplasm: Our results showed that the knockdown of CCND1b downregulated the ratio of CCND1b/a, inhibited the CDK4/CyclinD1‐pRB‐E2F1 signalling pathway and prevented tumour cells from passing through the G1‐S transition resulted in cycle arrest, thereby decreasing the chemoresistance (Figure 3C–F).