Therefore, we used immunofluorescence(IF) to detect mice liver metastases and found that the expression of macrophage M2 polarization marker CD206 was increased in LM/sh-GREM1 group, and the expression of CD206 was significantly inhibited in CLD treated mice liver metastases (Fig. 5D). Here, MRC1 is linked to congenital secretory chloride diarrhea 1.