In bacteria, Msc channels are directly gated by membrane deformations caused by changes in cell osmolarity, and initiate intracellular signaling. However, to date no eukaryotic mechanosensing receptor and/or channel have been unambiguously identified. Several families of ion channels, mostly non-selective calcium channels from the TRP family, have been implicated in mechanosensing in C. elegans, Drosophila and mammals, but it is still not clear if they are directly or indirectly gated by mechanical stress. For example, early observations suggested that TRPC6 channel could be directly AG-013736 activated by changes in membrane tension, but recent findings rather indicate that this channel is indirectly activated by the angiotensin II type 1 receptor. TRPP2 is a calcium channel that forms a complex with PKD1, and the PKD1/PKD2 complex has been implicated in intracellular calcium increases in mechanically stressed ciliated cells. However some studies indicate that the PKD complex may act rather by interacting with the cytoskeleton and regulating an as yet unidentified channel. In addition to TRP channels, metazoan candidates for mechanosensitive components include sodium channels of the ENaC family, two-pore domain potassium channels and bacterial Msc-like channels. The amoeba Dictyostelium discoideum is a model organism easily amenable to genetic analysis, and largely used to study cell migration and chemotaxis, as the core mechanisms involved in motility are largely conserved from amoebae to human cells. Several publications have reported that migration and physiology of Dictyostelium cells are modulated by mechanical stresses induced by a fluid flow, electrical fields or compression. Remarkably, the total number of putative ionic channels is extremely reduced in Dictyostelium compared to other organisms. The Dictyostelium genome contains only three genes encoding putative calcium channels potentially expressed at the cell surface or in endocytic compartments as well as one Msclike channel. In addition, one IP3 receptor is potentially present in the ER, and five P2X receptors are restricted to the contractile vacuole. Since P2X receptors are thought to play a specific role in the function of the specialized osmo-regulatory contractive vacuole, they were not considered further in this study. The low number of channels and the relative ease with which specific knockout strains can be generated and analyzed makes Dictyostelium a unique system by allowing a systematic comparative analysis of the role of each channel in mechanosensing. In this work, we showed by systematic comparative analysis of KO strains that in Dictyostelium, PKD2 is the most important protein for rheotaxis.