Given that Mac-1 (CD11b/CD18), mainly expressed in macrophages, is the receptor for ICAM1, to study whether RARRES1-overexpressing RCC cells can enhance the binding of ICAM1 to Mac-1 in macrophages, we cocultured RARRES1-overexpressing RCC cells and M1 macrophages in a Transwell system. Here, ICAM1 is linked to renal cell carcinoma.