Consistent with its greatly improved half-life in cell culture medium, PEG-TNYL-RAW inhibits ephrin-B2-induced tyrosine phosphorylation of endogenous EphB4 expressed in B16 melanoma cells with an IC50 value of 90 nM, and 2 μM peptide are sufficient to reduce receptor phosphorylation to undetectable levels (Figure 4A, B). Here, EPHB4 is linked to melanoma.