Further experiments on RCC cell lines - Caki-2 (primary tumor) and SK-RC-52 (metastatic tumor) – have shown that IGF-I enhances transforming growth factor (TGF)-beta signaling including phosphorylation and nuclear translocation of mothers against decapentaplegic homolog 2 (Smad2). The gene discussed is IGF1; the disease is metastatic neoplasm.