AKT1 and cancer: AKT mutations conferring constitutive activation are observed in many cancers (Shtilbans et al., 2008); mutations in the pten gene, disrupting the PI 3-phosphatase that opposes PI3K, also produce a high PIP3/PIP2 ratio, favoring activated AKT and hence cell proliferation in diverse cancers (Yi et al., 2005).