ERBB2 and neoplasm: RNA sample set 1 (35 NCI-Bari RNA samples) and RNA sample set 2 (66 age-matched UCSF samples) were combined to yield 101 RNA samples from ER-positive breast cancers, arising in the predefined younger (n = 53) and older (n = 48) age groups, well balanced for tumor size, nodal involvement, grade, PR status and ERBB2 status.