Accumulating studies reported that SKP2 could promote the degradation of several tumor suppressor proteins, including P27, P21, P57, and P130 and also degrade Forkhead box protein O1 by ubiquitination, a transcription factor in the FoxO family with the function of inducing cell cycle arrest, thus to promote the occurrence and development of tumors. Here, FOXO1 is linked to neoplasm.