We therefore combined the lists made with the two screening strategies creating a set of 894 probesets. A heatmap provides a visual representation of the relative abundances of transcripts of adult podocytes compared to E13.5, and E15.5 podocytes, as well as total kidney cortex. Many of the genes show a graded expression level, weakest at E13.5, stronger at E15.5, and then strongest in the adult podocyte. Fig. 2 also illustrates how some of the adult podocyte probesets are enriched compared to E13.5 but not total cortex, while others are enriched versus total cortex but not E13.5. For a complete inventory of the 894 genes, along with fold enrichments, see Table S1. Of interest, and validating the screen, a large number of genes previously associated with podocytes showed the greatest enrichments. To better define the molecular processes and biological functions carried out by the podocyte we analyzed the 894 gene list with the AbMole Dimesna ToppGene web tool. This software application searches for gene enrichments associated with specific molecular functions and biological processes. An interesting view of the podocyte emerged, with an unusual mix of functions. Given the extraordinary structure of the podocyte it is not surprising that a number of enriched genes were associated with the cytoskeleton. There were 65 cytoskeletal AbMole 28-demethyl-beta-amyrone binding proteins identified, and 39 genes involved in actin skeleton organization. Several other interesting molecular processes and biological functions emerged. Twelve genes encoded proteins involved in integrin binding, and another 44 were involved in calcium ion binding. The top biological processes to emerge from the ToppGene analysis included vesicle mediated transport, with 72 genes involved, actin cytoskeleton organization, regulation of signaling, neurogenesis, neuron projection development, axon guidance, biological adhesion, response to oxygen levels, neuromuscular junction, chemotaxis, phagocytosis, striated muscle cell differentiation, muscle contraction. For complete gene lists see Table S2. The biological process analysis again shows a strong neuronal character, but also some molecular features associated with muscle and phagocytes. We examined the possible muscle character of the podocytes in more depth, in light of their possible contractile role in counteracting the perfusion pressure of the capillaries. It is interesting to note that podocytes did express several myosins, including myo6, myo1e, myo1d, myo10 and myl6. Nevertheless, these are generally unconventional myosins that are more associated with vesicle transport and other movements along actin filaments rather than muscle contraction. Podocytes also showed strong expression of Tpm1, tropomyosin, which binds actin filaments in both muscle and non-muscle cells. It is interesting to compare the array results presented here with previous studies of the muscle nature of podocytes. Potential contractility of the podocyte has long been noted, and a more recent study examined in some detail the muscle characteristics of podocytes grown.