CDK4 and melanoma: This SASP contributes to the development of an immunosuppressive microenvironment by increasing the presence of MDSCs and Treg cells, which also inhibits the function of CD8 + T cells.19 CDK4/6 inhibitors in melanoma cause a potent SASP of TISnt fibroblasts, leading to the recruitment of Gr-1-positive immune cells that suppress antitumor immune response, thereby facilitating melanoma growth.115 Furthermore, irradiation triggered the expression of atypical MHC molecules, such as MICA/B and HLA-E, in senescent populations of both dermal fibroblasts and umbilical vein endothelial cells.