qRT-PCR analysis showed in CLL treated mice (Figures 1E,F), a downregulation of genes encoding for endothelial surface proteins (CD31, Cdh5, CD34), for signaling molecules (Notch4, Flt4, Jag2) (32), and transcription factors (TCF4 and KLF4) (44, 45) involved in endothelial differentiation. The gene discussed is TCF4; the disease is B-cell chronic lymphocytic leukemia.