We show that oncogenic RAS induces senescence in thyrocytes as judged by changes in cell morphology, activation of p16INK4a and p53/p21CIP1 tumour suppressor pathways, senescence-associated β-galactosidase (SA-β-Gal) activity, and induction of proinflammatory components including IL-8 and its receptor CXCR2. Here, CDKN1A is linked to neoplasm.