In CLL, this evidence shows that HSP70 expression is regulated by the modulation of HSF1 activity through the activation of RAS-regulated pathways (as previously observed in CML [17] and MM [18]), and suggests the HSP70/HSF1 interplay as an interesting target for anti-leukemic therapies. This evidence concerns the gene HSF1 and chronic myelogenous leukemia, BCR-ABL1 positive.