ERBB2 and central nervous system cancer: Previous studies in colon, breast, and ovarian cancers have shown that protein abundance cannot be reliably predicted from gene expression measurements.13–15 Direct measurement of protein markers, however, has proven to be robust and reliable prognostic and theranostic tools in many cancer types (eg, HER2-neu, ER, and PR in breast cancer), which has generated significant interest in proteomics within the glioma field.