PPBP and neoplasm: Interestingly, although neutralizing antibodies against CXCL7 do not directly affect the expression of target genes, immunohistochemistry (IHC) of mouse tumor sections showed that CXCL7 neutralizing antibodies suppressed CXCL7 expression (Figs. 3F, H), suggesting the existence of a positive feedback loop that sustains CXCL7 expression within the tumor microenvironment.