DNA-binding protein involved in S phase checkpoint control-coupled apoptosis by mediating p53/TP53-induced apoptosis. Has the ability to inhibit DNA synthesis and S phase arrest coupled to apoptosis. Has affinity to both double- and single-stranded DNA. By p53/TP53; direct transcription target of p53/TP53. The gene represented in this entry is involved in disease pathogenesis. Germline KLLN methylation is common among patients with Cowden syndrome or Cowden-like syndrome and is associated with increased risks of breast and renal cancer over PTEN mutation-positive individuals (PubMed:21177507).