Lastly, through exome sequencing, Li et al. observed loss of heterozygosity of CEACAM1, CEACAM3, CEACAM5, CEACAM6, CEACAM7, and CEACAM8 in breast cancer tumors that were associated with metastasis, suggesting that this closely-linked gene family regulates tumorigenesis and metastasis synergistically (Li et al., 2014). This evidence concerns the gene CEACAM8 and breast cancer.