We first compiled a panel of breast cancer cell lines of known molecular subtype including 2 CL cell lines; these were fixed in formalin and embedded in paraffin blocks to ensure that they were processed in a manner analagous to human tumor samples and profiled for ER, PR, HER2, CK5/6 and EGFR as previously described [16]. The gene discussed is ERBB2; the disease is breast cancer.