The complexity of the role of Lyn in B cells versus B lymphomas (negative and positive roles) is reminiscent of its negative role in normal myeloid cell development [11] and its positive role for the growth of chronic myeloid leukemia cells, where Lyn inhibitors are already being tested in clinic [70]. The gene discussed is LYN; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.