EDNRA and B-cell chronic lymphocytic leukemia: Blocking ETAR on CLL, by pretreating cells with 0.1 μM and 1 μM BQ-123 before co-culture, abrogated the pro-survival effect of endothelial cell contact, decreasing CLL viability to 26%±5% and 25%±4% respectively (p = 0.0005 and p = 0.0008, Figure 2C and Figure S2 in File S1).