SIRT1 and rheumatoid arthritis: Sirt1 preferentially de-acetylates p53 at K382 to have a profound negative impact on the capacity of p53 to induce expression of target genes involved in apoptosis such as PUMA and Bax. 19 The p53 de-acetylation caused by Sirt1 inhibits p53-dependent pro-apoptosis by increasing ubiquitination-mediated degradation of p53.4, 24 Evidence suggests that Sirt1 is highly expressed in RA-FLSs, which is positively related to RA severity.24, 25 Our study found that VD with TNF-α inhibited p53 de-acetylation, increased p53 acetylation and promoted p53-dependent pro-apoptosis.