Residues in CEACAM6 and CEACAM8 have been identified that are critical for CEACAM6 homodimerization as well as the formation of CEACAM6 and CEACAM8 heterodimers, which is important in preventing breast cancer cell proliferation (Kuroki et al., 2001; Iwabuchi et al., 2019). Here, CEACAM6 is linked to breast cancer.