TKI resistance has been associated with methylation of several promoters for sFRP1 in the Wnt pathway [112], or of the Src suppressor gene PDLIM4 [113], and of HOXA4. Studies in CD34+ progenitor cells indicate that methylation particularly concerns tumor suppressor genes and occurs very early during CML transformation before being markedly decreased in the last phase of the disease. Here, CD34 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.