WFDC1 and neoplasm: 55 Another in vivo study showed that PDGFRα+ CAFs isolated from a PDAC mouse model stimulated subcutaneous PDAC tumour growth in mice by 76%, while normal pancreatic fibroblasts inhibited tumour growth by 65%.56 Tumour growth-suppressive factors, such as whey acidic protein four-disulphide core domain 1 (WFDC1), were highly expressed in resting fibroblasts but downregulated in CAFs,57 suggesting that dormant fibroblasts might indeed suppress tumorigenesis.