CTNNB1 and liver cancer: PIK3CA encodes the active subunit of phosphatidylinositol 3-kinase (PI3K), which regulates cell growth, proliferation, differentiation, motility and survival (Figure 2).[12] Mutations in PIK3CA have been reported in 7% of liver cancer cases.[7] Preclinical and early clinical data suggest that activating mutations in PIK3CA may predict sensitivity to inhibitors of the PI3K/AKT mTOR pathway.[12-14] CTNNB1 encodes beta-catenin, a key component of the Wnt signaling pathway (Figure 2).