SNAI2 and lung cancer: MLL4 (H3K4 methyltransferase) induces the expression of Slug, UTX (H3K36me3 demethylase) induces the expression of ZEB1, and EZH2 (H3K27 methyltransferase) suppressed the expression of Twist in the analysis of immunohistochemical staining and qRT-PCR for the 46 paired samples of lung cancer and its brain metastasis in individual patients.