USP22 and neoplasm: Interestingly, in contrast to the prevailing view that USP22 is a universal oncogene, our recent results demonstrated a context-dependent tumor suppressor function of USP22 in colorectal cancer whereby loss of USP22 expression resulted in decreased SAGA-mediated H3K9ac on the PRKAA2 gene (which encodes the AMP-activated protein kinase-2) and a concomitant downregulation of its expression, thereby leading to activation of the mTOR signaling pathway6.