CXCL10 and neoplasm: In mice, truncation of CXCL10 by CD26 reduces the infiltration of T cells into tumor tissue [63] and towards intraperitoneally injected CXCL10 [52] and consequently impairs the natural antitumor immunity Administration of the CD26 inhibitor sitagliptin significantly improved the natural antitumor immunity of these mice and their response to existing immunotherapies.