HDAC9 and cancer: Noteworthy examples of these concepts are the relative success of drugs inhibiting multiple kinases and/or display off-target activities in the treatment of previously difficult-to-treat diseases such as renal and liver carcinoma, as well as cancer drugs that instead of hitting a single gene product, hit processes such as proteosome, heat shock protein 90 (Hsp90), and HDAC inhibitors [414].