RELA and osteosarcoma: As expected, osteosarcoma cells expressing lower levels of TNFR1, TNFR1 + RelA, TNFR1 + RelB, TNFR1 + c‐RelA, CUL4B, and CUL4B + RelA; SPD304‐treated cells; and p21‐overexpressing cells exhibited dramatically higher percentages of cells in the S phase (Fig. 7A–J).