To further examine the altered transcriptome in the early stage of BC development, we compared the abnormal transcriptome of Lhx4 null developing retinas with that of bipolar cell pseudo-time (Clark et al., 2019) and found that the expression of Bhlhe23, Grik1, Grm6, Scgn, Otor, Gsg1, and Samn1 in BCs was significantly decreased in Lhx4 null retinas at P6 (Figures 5C and 5D; Table S1). This evidence concerns the gene GRIK1 and breast cancer.