CDKN1A and lip and oral cavity carcinoma: In this regard, our findings provide a physiological basis by which FXR1 prevents cellular senescence through loss of p21 and upregulation of TERC. Our data also indicate that, overexpression of p21 alone is not sufficient for promoting senescence in oral cancer cells (Fig 6D and 6E); it also requires down-regulation of TERC (Fig 6D and 6E).