PTEN loss of function occurs in a wide spectrum of human cancers through various genetic alterations that include point mutations (missense and nonsense mutations), large chromosomal deletions (homozygous/heterozygous deletions, frameshift deletions, in-frame deletions, and truncations), and epigenetic mechanisms (e.g., hypermethylation of the PTEN promoter region) [21]. Here, PTEN is linked to cancer.