ESR1 and breast lobular carcinoma: ERβ1 protein expression (Figure 2) using 385p/AR385-10R ERβ antibody showed differential expression in BCa subtypes, with a higher expression in well-differentiated duct BCa and lobular carcinoma than poorly differentiated BCa, and a high ERβ1 protein expression in ERα-negative BCa with high co-expression of HER2/neu and p53 (Figure 2I–L).