ERBB2 and invasive ductal breast carcinoma: In view of the correlation of RAD21 expression with prognosis in grade 3 cancers, we examined RAD21 mRNA expression for its association with gene copy number, in an integrated array CGH and transcriptional dataset generated from 48 microdissected grade 3 invasive ductal carcinomas of luminal (n = 22), basal-like (n = 13) and HER2 (n = 13) subtypes [18].