A summary of the pathways transduced by the primary cilium. The primary cilium is indicated in yellow with its basis formed by the basal body. In response to fluid flow, Polycystin 1 (PC1) and Polycystin 2 (PC2) are able to control the cell cycle. The platelet-derived growth factor alpha (PDGFα) signaling controls cell cycle and is transduced through the primary cilium. Vangl2 and Inv localize to primary cilia. Vangl2 is important for the planar cell polarity (PCP) pathway. Inv is the molecular switch between the PCP and Wnt pathways. Sonic hedgehog (Shh) signaling acts through Smoothened (Smo) that localizes to the primary cilium.