In addition, although some studies have described forms of TGF-β with small molecular weight (for example 12.5, 25, 50, and 90 kDa in breast cancer tissue [44]), in humans, TGF-β is known to be synthesized and secreted in a biologically latent form as a high-molecular weight complex (135 kD) that is highly unlikely to be filtered in the absence of proteinuric glomerular disease [45, 46]. The gene discussed is TGFB1; the disease is breast cancer.