SIRT1 and diffuse large B-cell lymphoma: Consistently, IHC analyses revealed that Sirt1 is significant upregulated at protein level in all four DLBCL cell lines and in DLBCL patient tissues, compared with that of CD19+ purified peripheral blood from normal B cells or normal lymph node tissues (Figure 1D), suggesting that Sirt1 is upregulated in human DLBCL cells.