FOXO1 and cancer: In addition, high SKP2 endorses cancer progression through the activation of various growth and survival-signaling pathways, for example, PTEN, ARF, pRB, FOXO1, and high Her2/Neu, etc. SKP2 acetylation and phosphorylation regulates its SCF E3 ligase activity in the cytoplasm during cancer progression, and AKT phosphorylates SKP2 at Ser72 during metastasis.