TBX2 and breast cancer: Upregulation of G9a causes mono‐ or di‐methylation to lysine 9 residue of histone 3 (H3K9), resulting in an increase in the expression of TBX2, FBP1, PRC-2, and NF-κB and a decrease in the expression of DKK1, MYC, CDH10, Reptin, CASP1, ZEB2, RARRES8, and E‐cadherin in BC.