CCND1 and infection: To further validate that CCND1 promotes the resistance of CRC cells to chemotherapeutic drugs, the shCCND1 plasmid was constructed, and the expression of CCND1 was inhibited by lentiviral infection of HCT8/5-Fu and HCT8/DDP, and the knockdown efficiency was detected by RT-qPCR and western blotting (Fig 6A and 6B).