Many of the cancer linked mutations identified are located at two separate interfaces between the p110 catalytic and p85α subunits, one between the iSH2 domain of p85 and the C2 domain of p110α, and one between the nSH2 domain of p85 and the helical domain of p110α (Huang et al., 2007; Miled et al., 2007; Wu et al., 2009). Here, PIK3R2 is linked to cancer.