CDKN1A and osteosarcoma: Recently, we found that CUL4B was overexpressed in osteosarcoma and that the activated CUL4B formed an E3 ligase with DDB1, RBX1, and DCAF11, which further ubiquitinated p21 and caused p21 degradation, resulting in the disruption of cell cycle progression (Chen et al., 2017).