PDK1 and cancer: PI(3,4,5)P3 brings two PH domain-containing serine/threonine kinases, phosphoinositide-dependent kinase 1 (PDK1) and AKT into close proximity, phosphorylating AKT and thus activating it.37 AKT is the primary mediator of PI3K-initiated signaling and has a number of downstream substrates that may contribute to malignant transformation.13 HBA caused appreciable downregulation of pAKT in a dose-dependent manner in all the three cancer cell lines.