“…Many such serum constituents are known to be mitogenic on various other cell populations [12,15,16,20,32], Some of them have not yet been tested on Schwann cells, e.g., multiplication stimu lating activity and somatomedins [27,28] or platelet-derived growth factor(s) [15,23], while another (EGF) was found here to be in active. Since FGF is a potent mitogen for mouse Schwann cells it could, itself, be the serum constituent responsible for the similar effects of FCS.…”