CXCL9 and melanoma: In addition, ELISA analysis indicated that the CXCL9 protein concentration in melanoma was increased to 14.07 ng g−1 by NPTyr-C9AP treatment (Fig. 4a), and the serum CXCL9 concentration was correspondingly elevated to 0.26 ng ml−1 due to the diffusion of CXCL9 from the melanoma to the periphery (Supplementary Fig. 11).