IPO5 and cancer: The importins encoded by 5′TOP mRNAs, IPO5 and IPO7, are both specifically responsible for nuclear import of several RP subunits and are implicated as key contributors to cancer cell proliferation, tumorigenicity, and regulation of the p53 oncogenic pathway (Çağatay and Chook, 2018; Golomb et al., 2012; Zhang et al., 2019).