FAP and ductal breast carcinoma in situ: We found that the expression levels of FAP-α and α-SMA were significantly up-regulated in invasive breast carcinoma (97.5%, 38 in 39), compared with human ductal carcinoma in situ (DCIS, 33.3%, 7 of 20), suggesting that CAFs facilitated tumor metastasis in patients with breast cancer (Additional file 1: Figure S7).