SIRT2 and chronic obstructive pulmonary disease: Data showed that SIRT1 and SIRT6 were the only members of the sirtuin family down-regulated by the miR-34a mimic, with the mRNA expression of SIRT2, 3, 4, 5 and -7 being unaffected by the mimic (Fig. 4A), implying the importance of miR-34a in COPD.