In conclusion, it appears that at least the majority of CML/G0 cells overexpress genes usually associated with erythro-megakaryocytic development which is probably correlated with the thrombocytosis frequently seen in patients with CML and also with the spontaneous growth of erythroid colonies in vitro by CML progenitors in the absence of erythropoietin, whereas normal progenitors always require EPO [32]. This evidence concerns the gene EPO and thrombocytosis disease.