EYFP+ 5-HT neurons were sorted using a BD FACSAria into Trizol reagent and extracted RNA was Dnase I treated and purified using the RNA Clean & Concentrator-5 kit (Zymo). Purified total RNA was amplified with the SMARTer Ultra-low mRNA-Seq kit (Clontech) or Ovation RNA-Seq System V2 (NuGEN). Dissected YFP+ tissue between the mid-hindbrain boundary and rhombomere 4 of E12.5 to E15.5 hindbrains from Pet-1-/-; ePet-mycPet-1; ePet-EYFP embryos was quickly flash frozen on dry ice. Chromatin was isolated and immunoprecipitated using a ChIP grade, goat anti-Myc antibody (Abcam ab9132, Cambridge, MA, validation report at abcam.com) with proprietary protocols (Active Motif, Carlsbad, CA). RNA libraries were prepared for sequencing using either Clontech SMARTer RNA-seq (E11.5, E15.5C_WT, E15.5C_KO, PN) or NuGen Ovation RNA-Seq v2 (E15.5N_WT, E15.5N_KO). ChIP-seq libraries were prepared using standard Illumina ChIP-seq methods.