USP7 and neoplasm: Notably, TSPYL5 interacts with USP7 (ubiquitin specific peptidase 7) to reduce the tumor suppressor activity of p53, overriding p53-dependent proliferation arrest [12], promoting endothelial cell proliferation and angiogenesis [15], and protecting POT1 (protection of telomeres 1) from proteasomal degradation in ALT (alternative lengthening of telomeres)-positive cells [16].