ERBB2 and breast cancer: This study also quantified HER-2 gene amplification in 774 breast cancer patients using the next-generation sequencing assay and reported that patients with HER-2 overexpression or low expression had a significantly higher copy number amplification of other genes, including CDK12, retinoic acid receptor, alpha (RARA), and Speckle Type BTB/POZ Protein (SPOP), compared to HER-2− patients.