By using comparative genomic hybridization microarray analyses of human chromosome 17q12 in the ERBB2 amplicon, where GRB7 is located on the chromosome next to ERBB2, the copy number and expression levels of genes within the ERBB2 amplicon, such as GRB7 and ERBB2, were highly increased in human breast cancers [9], gastric cancers [10], high grade intraepithelial neoplasia, and invasive Barrett’s carcinoma [64]. Here, GRB7 is linked to breast cancer.