Besides, considering that the half-life of p21 proteins is relatively short, with its stability predominantly regulated by posttranslational modifications such as ubiquitination and phosphorylation 20, 39, we speculate that USP44 plays its tumor suppressor function in thyroid cancer cells by regulating the protein stability of p21 via deubiquitination. The gene discussed is CDKN1A; the disease is thyroid gland carcinoma.