To explore whether cells lacking CEA expression is intrinsic different from CEA+ cells in tumorigenic capacity, we carried out immunostaining for CEA in CRC cell lines (i.e., LoVo and SW48 cells) with anti-CEA antibody, and then employed MACS and/or FACS to acutely purify out CEA+ and CEA−/lo CRC cells (Figure 2A). The gene discussed is CEACAM5; the disease is colorectal carcinoma.