HDAC6 and cancer: Previous study indicated that p53 plays an essential role in SAHA-induced apoptosis in MCF-7 cells [40], whereas other studies suggested that SAHA shows preferential cytotoxicity in several p53-mutant cancer cells through inhibition of the HDAC6-Hsp90 chaperone axis [41], indicating the complexity of mechanism by which SAHA medicates apoptosis in wild type and p53-deficient tumors.