PTEN and neoplasm: PTEN is a tumor suppressor that has been found to have a number of alterations in HNSCC, including nonsense [2, 13, 14], missense [2, 13, 15], loss of heterozygosity [16, 17], hemizygous deletion [39], intron [14], and splice site single nucleotide polymorphisms [2], as well as reduced expression [16].