HDAC9 and non-small cell lung carcinoma: Until now, there were 18 mammalian HDAC isoforms have been identified in humans, which could be divided into four classes according to their homology to yeast prototypes.14 Among all of the HDACs, HDAC1, -3, -6, and -8 have been frequently revealed to be closely related to tumorigenesis.14 Here, we found that HDAC activity was increased in paclitaxel-resistant NSCLC cells in comparison with parental cells, and that resulted in an enhanced proliferation and tumorigenesis capability, suggesting a novel biology role of HDAC in drug resistance.