Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), also referred to as mutated in multiple advanced cancers (MMAC1) and TGF-β regulated and epithelial cell enriched phosphatase (TEP1), was first discovered in 1997.1–3 Since its discovery, an entire network of interconnections to various other cellular pathways has been uncovered but its role continues to evolve. PTEN is frequently inactivated in somatic cancers and is ranked the second most mutated tumour suppressor gene after p53.4 5

This article highlights the important aspects of structure, function, mutations and role in cancer that are of relevance to the practicing pathologist. For more detailed information on these aspects the reader should refer to recently published articles.