CSK and neoplasm: Among these five successfully validated genes, we selected the C-terminal Src kinase (CSK) gene for further investigation, mainly because of the significantly highest demethylation effect on CSK after DAC treatment in PDX-36 tumors, the relevance of CSK biological function as a negative regulator of non-receptor Src family kinases, and the involvement of CSK in many key signaling pathways along with its anti-tumor activity [39, 40].