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Figure S4. Real-time PCR analysis of the expression profile of Xenopus TRPC1 and BMPRII in Xenopus neural tubes. (A) Primers specific to Xenopus β-actin, TRPC, and BMPRII are designed by PrimerExpress software and tested in RT-PCR using RNA sample from stage 26 Xenopus neural tube tissues. -RT, RNA sample without reverse transcriptase. (B) Quantitative real-time PCR was performed using the SYBR green system (Applied Biosystems), and the data were normalized by the expression level of β-actin. The RNA expression level of the stage 18 neural tube tissues was set as 1. Different stages of developing Xenopus embryos and their correlations with the specific stage of commissural axon projection are depicted in the schematic diagram based on the published results (Moon, M.S., and T.M. Gomez. 2005. Dev. Biol. 288:474-486; Shim, S., E.L. Goh, S. Ge, K. Sailor, J.P. Yuan, H.L. Roderick, M.D. Bootman, P.F. Worley, H. Song, and G.L. Ming. 2005. Nat. Neurosci. 8:730-735). Error bars represent SEM. RF, roof plate; FP, floor plate.