CDKN1A and neoplasm: p16Ink4a and p21Waf1/Cip1 could suppress tumor progression by inducing cellular senescence, the deletion of p16Ink4 and p21Waf1/Cip1 reduces CX3CR1 expression and inhibits monocytic-MDSCs (Mo-MDSCs) accumulation in tumors expressing CX3CR1, hence suppresses the tumor proliferation in mice model.