KCNJ2 and Tremor: Because expression of Kir2.1 with R21G03-Gal4 led to tremor (Fig. 1G), we made use of a heat-shock (hs)-inducible Kir2.1 transgene (von Philipsborn et al., 2011), which allowed us to inactivate tremor neurons starting at various time points (Fig. 2Bi).