During the process of cancer development, abolishment of KLF4 methylation leads to upregulated Bax levels and reduced expression levels for a set of oncogenes such as cyclin D2, cyclin B1, Myc, EGF and IGF1 because of enhanced destruction of KLF4 that suppresses transformation of mammary gland epithelial cell and, accordingly, breast tumour progression. The gene discussed is KLF4; the disease is cancer.