We previously showed that the expression of the SRC family kinase (SFK) LYN was an essential factor for CLL progression in vivo as demonstrated by adoptive transfer experiments in the Eμ-TCL1 transgenic mouse model for CLL19, which could be partially attributed to the failure of LYN-deficient macrophages to fully support CLL cell survival20. The gene discussed is LYN; the disease is B-cell chronic lymphocytic leukemia.