  In one paradigmatic example, Vogelstein and his group collected tissue samples (premalignant polyps) from patients with a familial or inherited form of bowel cancer (FAP, or familial adenomatous polyposis). They discovered that mutations to genes associated with various cancers accumulated in series of steps, what has been called the “Vogelstein cascade.” The study of familial or strongly inherited forms of cancer (cancers that appear at relatively young ages, and occur in families) has enabled the identification of several genes, mutations to which (whether inherited or acquired during somatic cell division) play a role in cancer: APC, RB, and p53 (associated with familial adenomatous polyposis, retinoblastoma, and Li Fraumeni syndrome, respectively).