TP53 and sarcoma: It has been recently reported that IU1-mediated inhibition of USP14 results in the increased ubiquitination of constitutive photo-morphogenesis 9 (COP9) signalosome subunit 5 (COPS5), a key negative p53 regulator, resulting in tumor regression of autochthonous T-lymphomas and sarcomas in p53-deficient mice without affecting normal tissues [216].