Notably, USP28 contains two predicted phosphorylation sites for PRKD1 (consensus sequence LxRxxS, [Nishikawa et al., 1997]; Figure 5A), a serine/threonine protein kinase (Johannes et al., 1994) isolated in our RNAi screen (Figure 2—figure supplement 1) that is dysregulated in a variety of cancers (Sundram et al., 2011). Here, AKT1 is linked to cancer.