The following information accompanied stocks donated to the Bloomington Drosophila Stock Center by Chun-Chao Chen and Ann-Shyn Chiang, National Tsing Hua University. P{UAS-RA.cs2}CC (FBrf0217453, Chen et al., 2012, Science 335(6069): 678--685) was obtained by remobilizing P{UAS-RA.cs2}39 (FBrf0076758 == Allen et al., 1993, J. Neurogenet. 8: 221). In the presence of OK107-GAL4 at low temperatures, deformed mushroom bodies (MBs), indicating leaky activity, are seen with P{UAS-RA.cs2}39, but not P{UAS-RA.cs2}CC. Two types of MB defects are noticed: axons crossing the midline and reduced number of vertical axons. In some severe cases, the alpha' lobe was missing. At 30 degrees C, P{UAS-RA.cs2}CC was as effective as the P{UAS-RA.cs2}39, causing severe MB defects. P{UAS-RA.cs2}39 is a viable and fertile insertion on the third chromosome P{UAS-RA.cs2}CC is a viable and fertile insertion on the third chromosome -- Annette Parks, Ph.D. Bloomington Drosophila Stock Center http://flystocks.bio.indiana.edu