PKB is also known as Akt. Akt is a serine/threonine-specific protein kinase that plays a critical role in controlling the balance between survival and death pathways in cells. The Akt kinase family comprises three highly homologous isoforms: Akt1 (PKBα), Akt2 (PKBβ), and Akt3 (PKBγ) [4,14].

The Akt signaling pathway or PI3K-Akt signaling pathway is a signal transduction pathway that promotes survival and growth in response to extracellular signals. Key proteins involved are PI3K (phosphatidylinositol 3-kinase) and Akt (protein kinase B).

PKB activates mTORC1 indirectly by phosphorylation of tuberous sclerosis complex 2 (TSC2) in the TSC1/TSC2 dimer. Once mTORC1 is activated, it initiates a negative feedback loop that inhibits PKB by the negative regulation of IRS1 via activation of p70 ribosomal S6 kinase 1 (S6K) [21].

PI3K-Akt Pathway is an intracellular signal transduction pathway that promotes metabolism, proliferation, cell survival, growth and angiogenesis in response to extracellular signals. This is mediated through serine and/or threonine phosphorylation of a range of downstream substrates.

Membrane binding is required and sufficient for Akt phosphorylation on T308 and S473, which is essential for Akt activity (Alessi et al., 1997, Sarbassov et al., 2005).

The KRAS gene belongs to a class of genes known as oncogenes. When mutated, oncogenes have the potential to cause normal cells to become cancerous. The KRAS gene is in the Ras family of oncogenes, which also includes two other genes: HRAS and NRAS.

Fully active PKB/Akt mediates numerous cellular functions including angiogenesis, metabolism, growth, proliferation, survival, protein synthesis, transcription, and apoptosis (as shown in Fig. 2).

The serine/threonine protein kinase PKB (also known as Akt) is thought to be a key mediator of signal transduction processes. The identification of PKB substrates and the role PKB phosphorylation plays in regulating these molecules have been a major focus of research in recent years.

PKB/Akt binds to PIP3at the plasma membrane, allowing PDK1 to access and phosphorylate T308 in the “activation loop,” leading to partial PKB/Akt activation (Alessi et al. 1997).

The Ser and Thr kinase AKT, also known as protein kinase B (PKB), was discovered 25 years ago and has been the focus of tens of thousands of studies in diverse fields of biology and medicine.