Expression of TGF-β pathway genes in control (CN) and HER-2 overexpressing (H2) breast cancer cells. Northern analysis of HER-2 mRNA and transforming growth factor (TGF)-β markers in MCF-7, ZR-75-1 and MDA-MB-231 cells with (H2) and without (CN) HER-2 overexpression. Message levels were assayed from 10 ug of total RNA. Asterisks indicate consistent and significant down-regulation (> 2-fold as measured by phosphorimager quantification). The image of the 28S and 18S ribosomal RNA bands from the ethidium bromide stained gel is shown as a loading control.