GRIK1 and breast cancer: The expression of Scgn (a broad CBC marker), Grm6 (a pan-ON-BC marker), Fezf2 (type 1a, 1b, 3a, 3b, and 4 BCs), and Grik1 (Type 2, 3a, 3b, and 4 BCs) was significantly reduced in the Lhx4 null retina at P6 and P7 (Figure 5E).