To validate GREM1 and ISLR expression in human CRC CAFs, we performed RNA in situ hybridization (ISH) on CRC patient samples and confirmed that both GREM1 and ISLR are highly expressed by fibroblastic cells in the human CRC stroma compared to the normal colorectal stroma (Figure 1C and Supplementary Figure 2). Here, ISLR is linked to colorectal carcinoma.