CEACAM1 and neoplasm: Immunohistochemical staining of paraffin embedded tumor tissue demonstrated the stability of the CEACAM1 knockdown in the subcutaneous tumors: Little to no CEACAM1 protein could be shown in the MeWo CEACAM1 kd tumors whereas high CEACAM1 was detected in the MeWo Luc tumors (Fig. 2C).