BCL2 and neoplasm: In addition, genetic depletion of USP13 using clustered regularly interspaced palindromic repeats (CRISPR)/Cas9, or pharmacological inhibition of USP13 by a small-molecule inhibitor spautin-1, markedly downregulates MCL1 protein expression and shows synergistic effects against tumor cells in combination with ABT-263, a selective antagonist of BCL-2 and BCL-XL.