From our studies, first focused to clarify whether various cell types sharing the same embryonic origin (bone marrow stromal cells, osteoblasts, fibroblasts) affect survival and expansion of the leukemic B cell clone, we identified HGF as a novel factor, released from cells of the CLL-microenvironment, capable of protecting leukemic cells from apoptosis [21]. The gene discussed is HGF; the disease is B-cell chronic lymphocytic leukemia.