CASP9 and neoplasm: PI3K signaling pathway covers a wide and complicated network critical for the regulation of protein expression [41–43], and a series of factors belonging to different downstream functional pathways is associated with the pathway, for example, GSK3β, FOXO3A, caspase-9, and P53, which are involved in cell apoptosis and tumor suppression [44–49]; therefore, inhibition of a specific subunit is considered safer than inhibition of several nonspecific targets that operate together in PI3K-associated signaling pathways.