CEACAM1 and cancer: For example, reinsertion of CEACAM1 isoforms in colorectal and prostate CEACAM1-negative tumor cells inhibits xenograft tumor development in syngeneic mice, suggesting that CEACAM1-L behaves as a tumor suppressor protein; on the contrary, CEACAM1-L overexpression in tumors correlates with metastatic spread in other types of aggressive cancers, such as hepatocellular cancer [43], melanoma, non-small cell lung, gastric, thyroid, and bladder cancers [19].