CDKN1A and neoplasm: The mammalian forkhead transcription factors in the O class, including FOXO1 and FOXO4, are considered to be tumour suppressors due to their proapoptotic and anti‐proliferative effects.37 FOXO proteins translocate to the nucleus and upregulate a series of target genes, such as certain cyclin‐dependent kinase inhibitors (p21Cip1 and p27Kip1).