Fig. 4.

(A,B) A method used to radiolabel proteins made by Schwann cells, which are then fed to RGCs. The Schwann-cell-derived factors are taken up by RGCs and then isolated by fluorography. (B) Radiolabelled proteins in Schwann cell conditioned medium (lane 1) and after passing through a spin column to remove unbound radiolabel (lane 2). Lanes 3 and 4 show the residual radiolabelled SCM after incubation with retinal ganglion cells (different preparations). Lanes 5 and 6 show two different exposures of RGC lysates after 24 h incubation, showing a number of radiolabelled bands, including a clear band at 40 kDa (indicated by arrow), which has been taken up by RGCs from the Schwann cell conditioned medium.