Cancers with PTEN loss show increased activity of the PI3K-p110β (PIK3CB) isoform, which preferentially activates AKT2 [257, 258], while cancers with increased activation of SRC-family kinases (SFKs) secondary to RTK stimulation show increased activation of another PI3K isoform, PI3K-p110α (PIK3CA), that activates AKT1 [259]. This evidence concerns the gene PTEN and cancer.