CACUL1 and osteosarcoma: Regarding the treatment of osteosarcoma, studies have found that Cullin 4b (CUL4B), a key member of the Cullin-RING E3 ligase, has been shown to interact with DNA damage-binding protein 1 (DDB1) and Cullin-4-associated factor 13 in human osteosarcoma cells to form an E3 complex that degrades the tumor suppressor PTEN, thereby promoting cell growth.