CXCL9 and melanoma: The deletion of PTPN2 in B16F10A melanoma or AT3 mammary tumors in C57BL/6 mice can promote IFN-induced STAT-1 signaling and the expression of STAT-1 target genes, including those encoding chemokines such as CXCL9 and antigen presentation genes such as MHC-I (H2k1) to facilitate T cell-mediated anti-tumor immunity6,10.