FAP and idiopathic pulmonary fibrosis: Interestingly, ‘CCL19+ adventitial fibroblasts’ and ‘CCN3+ adventitial fibroblasts’ overexpressed fibroblast activation protein (FAP), a marker of activated fibroblasts and cancer-associated fibroblasts, including in canine idiopathic pulmonary fibrosis and canine lung cancer (32).