23 Senescent cells rely heavily on persistent p16 expression to maintain the senescent state.18 RB1 loss in the thyroid results in cellular senescence with p16 induction being important for antagonizing thyroid carcinogenesis.19 However, in contrast to the thyroid, cellular senescence was not induced in RB1-deficient lung epithelial cells despite robust p16 expression. This evidence concerns the gene RB1 and thyroiditis.