Supplementary Figure 4: Identification of cleavage sites within Myl9 mRNA and Todr1 mRNA.

(a) Schematic of 5’P capture experiment. PolyA transcripts were purified from total RNA isolated from lineage-depleted bone marrow cells. An adaptor was ligated specifically to transcripts exhibiting a 5’ monophosphate (a mark of endonucleolytic cleavage) and reverse transcribed. Tiled PCRs were then performed using a forward primer in the adaptor and reverse primers within Myl9 and Todr1 mRNA. Thus, PCR products could only be obtained if Myl9 and Todr1 contained a 5’ phosphate. PCR products were Sanger sequenced. The junction between the adaptor and mRNA denoted the original cleavage site. (b) Location of cleavage sites detected in Myl9 and Todr1 mRNA. Blue and red text denote stem or loop structure, respectively.