CDKN1A and prostate cancer: They isolated the pentacyclic triterpenoid plectranthoic acid that far exceeded metformin in terms of AMPK activating properties; when applied on PCa prostate cancer cells, plectranthoic acid inhibited cell proliferation and disrupted cell cycle in G0/G1 phase by up-regulating cyclin kinase inhibitors (p21/CIP1, p27/KIP1) as well as induced apoptosis by the suppression of the mTOR/S6K signaling pathway.