AKT1 and breast cancer: Because activity and expression of the cdk-inhibitors and growth suppressors p21 and p27 are controlled by PTEN and Akt [25, 26], breast cancer cells with control shRNA (low PTEN, high phospho-Akt) had low levels of p21 and p27 whereas cells with TMEPAI knockdown (high PTEN, low phospho-Akt) had increased p21 and p27 basally as well as with TGF-β (Fig. 5A and 5B).