on data, the proportion of Pax62/Ccnd1+ RG/BG precursors/cells among all Ccnd1+ and Pax6+ cells was analyzed with a logistic model for the influence of treatments, considering the grouping of the data according to different experiments; the R package lme4 was used for these calculations. Confidence intervals for the proportions were calculated with a random intercept-only model. Western blot Brain tissues were isolated from 8 weeks old Fgfr2lox/lox, heterozyote Nestin-Cre;Fgfr2+/lox and homozygote Nestin-Cre;Fgfr2lox/lox mice, and homogenized in RIPA buffer ). Total protein concentration was determined with the Pierce BCA Protein Assay, and 50 mg total protein per sample were separated in 10% NuPAGE Novex precast gels and blotted onto PVDF membranes. Blots were blocked in 4% skim milk in TBST and probed with rabbit anti-Fgfr2 and anti-hypoxanthine guanine phosphoribosyl transferase antibodies. Membranes were developed in ECL substrate and exposed to Hyperfilm ECL. CbA microexplant cultures CbA microexplant cultures were prepared essentially as described by Kunemund et al. , with some modifications to account for the embryonic tissues and the smaller size of the CbA. Briefly, cerebellar primordia were isolated from E16.5 CD-1 embryos, cut into small pieces of equal size, and plated onto poly-D-lysine and laminin coated coverslips in Neurobasal medium supplemented with 2 mM Lglutamine, 1x B27 nutrient mixture, 100 Units/ml penicillin, 100 mg/ml streptomycin, and 200 nM INCB-24360 chemical information ascorbic acid. Immediately after plating, 100 ng/ml recombinant human FGF9 protein in bovine serum albumin, 20 mM InSolution SU5402 in dimethyl sulfoxide or 0.0001% BSA and 0.1% DMSO were added to the medium. Microexplants were incubated at 37uC in a humidified 5% CO2 atmosphere for 36 h, and then fixed in 4% paraformaldehyde, processed for Ccnd1 and Pax6 ICC as described before and counterstained with DAPI. Results Fgfr2 deficiency leads to locomotor deficits and an aberrant cerebellar organization in adult mice To establish the function of FGFR2 in developing neural progenitors, we generated Nestin-Cre;Fgfr2lox/lox 16177223 conditional 16041400 knockout mice, in which deletion of exon 5 leads to a premature stop codon in exon 6 and truncation of the FGFR2 protein at the extracellular Ig-like II domain. Fgfr2 exon 5-specific mRNA was only detected in the choroid plexus but not in the cerebellum of adult Fgfr2 cKO mice, and full-length FGFR2 protein was 
not detectable in the brains of these mice using an antibody raised against the C-terminus of FGFR2. Adult Fgfr2 cKO mice were viable and fertile; to assess their locomotor abilities, we tested these mice on the modified hole board and rotating rod. In the mHB test, Fgfr2 cKO males showed a significantly decreased maximum velocity and reduced total distance travelled, indicating an altered horizontal locomotion. The mutant males also showed a significantly increased latency to the first rearing and reduced rearing frequency on board in the middle of the arena, indicating an altered vertical locomotion when this was not supported by the arena wall. However, the Rotarod performance of the Fgfr2 cKO males was not significantly different from control males, although we noted some variation in the latencies to fall from the Rotarod among the Fgfr2 cKO males. Because of these results, we focused our further analyses on the cerebellum of the Fgfr2 cKO mice, although we cannot exclude that the loss of FGFR2 in other brain regions of these mice also c
