Figure 5.

Cytosolic and nuclear β-catenin is observed in basal-like carcinoma in situ lesions. The subcellular localization of β-catenin was analyzed in 54 in situ carcinomas, composed of four molecular subtypes (40 luminal A, 3 luminal B, 5 basal-like, and 6 HER2⁺/ER⁻). Like invasive cancers, there was no segregation of membrane-associated β-catenin (A) among different subtypes of carcinoma in situ. However, a higher percentage of basal-like tumors expressed cytosolic (B) and nuclear (C) β-catenin (5/5 for both) than luminal A (7/40 and 0/40, respectively), luminal B (1/3 and 0/3, respectively), and HER2⁺/ER⁻ lesions (4/6 and 2/6, respectively). P < 0.001.