PAIP1 and cancer: Knocking down PAIP1 in a variety of cancer cell lines can inhibit the proliferation and metastasis of cancer cells, and/or induce apoptosis and cell cycle arrest (Bi et al., 2021; Guan et al., 2019; Li et al., 2019; Piao et al., 2018; Wang et al., 2019b; Wang et al., 2019c; Xie et al., 2020).