- Rat skeletal myoblasts and arterial smooth muscle cells express the gene for the A chain but not the gene for the B chain (c-sis) of platelet-derived growth factor (PDGF) and produce a PDGF-like protein. Sejersen, T., Betsholtz, C., Sjölund, M., Heldin, C.H., Westermark, B., Thyberg, J. Proc. Natl. Acad. Sci. U.S.A. (1986)