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, purchase PD-0325901 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 in culture . Three muscle markers, smoothelin, calponin and myocardin were detected by three methods, microarray, western blot and immunofluorescence. Several other genes associated with smooth muscle differentiation were also seen elevated in expression in podocytes by as measured by microarray. Surprisingly, our microarray analysis of in vivo podocytes provided somewhat disparate results. We observed Cnn1 expression at essentially background levels in adult podocytes, although slightly above background at E13.5 and E15.5. Myocd was expressed only at background levels in podocytes for all times examined. Similarly Smtn, , was just slightly above background at all times. In addition for several other muscle function genes previously observed expressed in podocytes , we saw little, if any, expression. Neb, Rrad, and Ryr2 were at background levels, while Fhl2, Adam8 and Id1 were just slightly above background . Id2 showed moderate expression in developing podocytes, but was off in adult, and Aebp1 gave low level adult expression.