To confirm that p16 expression is required for senescence induction by IR in PR55α knockdown cells, we utilized the AsPC-1 pancreatic cancer cells, which carry a homologous deletion of the CDKN2A locus [37] and thus lack both p16 and p14 expression (Figure 7A). The gene discussed is CDKN2A; the disease is familial pancreatic carcinoma.