In addition, they promote the in vitro proliferation of the K562 cell line and CD34+ cells obtained from newly diagnosed CML patients [189], which suggests that MDSCs, in addition to their immunosurveillance protection, may increase the number of CML cells and exacerbate the development of CML disease [193]. This evidence concerns the gene CD34 and chronic myelogenous leukemia, BCR-ABL1 positive.