We investigated the p53 phosphorylation status at Ser15 also in CD34+ from cord blood and from leukapheresis product, observing a similar phosphorylation levels when compared to CD34+ cells obtained from CP-CML (data not shown), thus suggesting a possible role of the endosteal niche in controlling p53 phosphorylation. Here, CD34 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.