Conservation of the Myod1 5′ UTR stabilizes processed Myod1 mRNA. (a) Schematic of Myod1 mutants. ‘Full’ consists of full-length Myod1 DNA. ‘5'del’ and ‘3'del’ are mutants with deleted 5′ UTRs and 3′ UTRs, respectively. In ‘Mut1,’ both 55A and 60A were replaced with C. In ‘Mut2,’ 80A was replaced with C. ‘6b-del’ carries a 55A to 60A deletion. ‘CDS’ contains only Myod1 CDS (i.e. the 5′ UTR, 3′ UTR, and all introns were deleted). (b) qRT-PCR analysis of total Myod1 RNA with seven Myod1 mutants. NIH3T3 cells were transfected with vectors shown in (a), and total Myod1 RNA levels were analysed at days 0, 3, 6 and 12 using a primer set within exon 1. Data are represented as the mean ± s.d. (n = 3). (c) Accumulation levels of processed Myod1 mRNA. Processed Myod1 mRNA levels were analysed using a primer pair between exon 1 and exon 2. Processed Myod1 mRNA was normalized to total Myod1 RNA. Data are represented as the mean ± s.d. (n = 3).