AKT1 (v-akt murine thymoma viral oncogene homolog 1) is responsible for the phosphorylation and cytoplasmic localization of CKDN1A (cyclin-dependent kinase (CDK) inhibitor 1, also referred to as p21). However, p21 is one of the CDKNs which normally resides in the nucleus and its cytoplasmic localization, mediated by AKT1, is common to various cancers where it suppresses proteins essential for apoptosis. Studies show th at up-regulation of AKT1 serves as a poor prognostic marker in breast cancer, which however, depends upon factors including population, hormone receptor status, and hormonal or trastuzumab therapy status.
