First, CDK4/6 inhibitors downregulate E2F transcription factor-related gene expression and upregulate major histocompatibility complex class I molecule expression in breast cancer cell lines [52]; CDK4/6 inhibitors activate endogenous retroviral components in tumor cells, stimulating the production of type III interferons to promote tumor antigen presentation [52, 53]. Here, CDK4 is linked to breast cancer.