Inhibition of HDAC1, 2, 3, 6, 8, and 10 by PCI24781 could enhance the mevastatin-induced inhibition of cell proliferation, whereas inhibiting HDAC3, 6, and 8 by RGFP966, tubacin, and PCI34051, respectively, or HDAC4, 5, 7, and 9 by MC1568, and knocking down HDAC10 and 11 by siRNAs, failed to do so (Figure S1), suggesting that HDAC1 or HDAC2 or both was involved in the pan-HDAC inhibitor-induced enhancement of the anti-cancer effects of mevastatin. Here, HDAC1 is linked to cancer.