A recent comprehensive analysis of the expression of claudins-1, -3, -4, -7 and -8 in high-grade invasive breast cancer, including several molecular subtypes, demonstrated the differential expression of claudins according to molecular subtype, showing increased claudin-7 and -8 in luminal tumors (estrogen positive) and increased claudin-1 and-4 in basal-like tumors [13]. The gene discussed is CLDN1; the disease is invasive breast carcinoma.