Interestingly, MDM2 was bound to RB through a central acidic domain in U20S, C33A, SAOS-2 cells (153), and could promote proteasomal degradation of RB in cells of osteosarcoma, cervical cancer, non-small cell lung cancer and temperature-sensitive murine ts20 cells (153, 154). Here, RB1 is linked to non-small cell lung carcinoma.