FAP and cancer: Interestingly, the expression of fibroblast activation protein (FAP) in CAFs in multiple cancer types was shown to be associated with recruitment of immunosuppressive cells: In a mouse model of hepatic cancer, a subset of FAP+ fibroblasts had an inflammatory phenotype directed by STAT3 activation and increased CCL2 expression, resulting in enhanced recruitment of CCR2-expressing circulating MDSCs and enhanced tumor growth (38).