SIRT6 and cancer: Furthermore, although we did not find significant differences in SIRT6 transcript levels between PHG and IHG tumors (either in our and TCGA cohort), nor between different stages of MIBC, Wu et al. reported that SIRT6 protein levels declined significantly from T2 to T4 MIBC, which also suggests that the functional importance of sirtuins may change along cancer progression [28].