Netrin-1 and DCC expression in Pbx1 null and wild type embryos. In situ hybridization using digoxigenin-labeled riboprobes against netrin-1 (A, B) and DCC (E, F), immunohistochemistry with antibodies against TH (C, D) on E14 mouse coronal section of wild type (A, C, E) and Pbx1−/− mutants (B, D, F) at level of midbrain. (A, B) Identical expression of netrin-1 in the ganglionic eminence (GE) of wild type (A) and Pbx1-deficient (B) embryos. (C-F) The parallel TH and DCC stained sections reveal DCC expression in wild type mesDA neurons, but no expression in Pbx1-deficient embryos at the same level. Dorsal to the top. Scale bars = 300 μm. (G) Quantitative PCR using DCC- and netrin-1- specific primers and probes on mRNA extracts from E13.5 ventral midbrain from Pbx1+/+ and Pbx1−/− mutants. Expression levels are relative to the housekeeping gene RLPL0, values are expressed as 2-ΔCt mean ± standard error of the mean; n ≥ 4 for each experiment(*P <0.05). mesDA: mesencephalic dopaminergic.