USP22 and neoplasm: In most tumors, high expression of USP22 predicts a poor prognosis (Hu et al., 2015; Lim et al., 2020), and USP22 also been shown to promote tumor proliferation, invasion and drug resistance through a variety of substrates, including PD-L1 (Huang et al., 2019; Huang X. et al., 2020; Wang et al., 2020), RAS activator son of sevenless 1 (SOS1) (Lim et al., 2020), BMI1 (Ma et al., 2017; Qiu G.Z. et al., 2018; Yuan et al., 2019; Qiu et al., 2020), MYC (Liu H. et al., 2019; Zhang K. et al., 2019), and COX-2 (Xiao et al., 2015).