Fig. 1. Upregulation of FGF2 protein levels in podocytes during post-mitotic differentiation. (A) Distribution of FGF2 proteins in differentiating glomeruli in a mesonephric kidney (isolated from a stage 21/22 chicken embryo). (B) Detection of BrdU-positive proliferating cells in a section adjacent to the one shown in A. Arrows in B point to groups of nonproliferating podocytes expressing high levels of FGF2 proteins (arrowheads in A). (C) Conditionally immortalised MPC cells express only low levels of FGF2 proteins during proliferation (permissive conditions). (D) High levels of nuclear FGF2 proteins accumulate in post-mitotic and differentiated MPC cells (grown for 7 days under nonpermissive conditions). (E) Expression of all three FGF2 protein isoforms is upregulated in differentiated MPC cells. SYN, synaptopodin, a marker for differentiated podocytes. (F) Cellular fractionation of proliferating and differentiated MPC cells reveals preferential nuclear accumulation of the two large FGF2 isoforms (21.5 and 22 kDa) in differentiated MPC cells (right panel). By contrast, the 18 kDa FGF2 isoform is detected in all three fractions. Cyto, cytoplasm; Diff, differentiated cells; JUN, c-Jun as a marker for the nuclear fraction; note downregulation in differentiated cells. Mem, membrane; Nuc, nucleus; Prol, proliferating cells; TUB, 
-tubulin as a marker for the cytoplasm; note upregulation in differentiated cells. Equal amounts of protein were used for all samples shown in panels E and F.
