Standard 5’ RACE was performed exactly as described in [21 (link)]. 25% of the ligation reaction was reverse transcribed (Superscript III, Life Technologies) using the manufacturer’s gene specific primer protocol (Table S1). After RNase H treatment, cDNAs were amplified using nested PCR with the indicated (Table S1) primers. Primary nested PCR products were purified using DNA Clean and Concentrator-5 columns (Zymo). Secondary PCRs were performed using CAGE site targeting primers (Table S1) as in [21 (link)], column purified, cloned into the pGEM-T-easy vector system (Promega), transformed, plated onto plates containing ampicillin, Isopropyl β-D-1-thiogalactopyranoside (IPTG), and 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal), and incubated at 37°C overnight. White colonies were assayed by colony PCR using primers complimentary to T7 and SP6 promoter sequences (Table S1). Products were separated using 2% agarose gels and ~300+ bp inserts were Sanger sequenced at the OSU Genomics Shared Resource. Sequences lacking RACE adaptors or those mapping to ribosomal RNA were discarded, and adaptor-containing sequences were identified using NCBI’s Basic Local Alignment Search Tool (BLAST) and splice variants were assigned using NCBI databases.