Flies carrying the Prm^S10A.cLa transgene do not exhibit any significant differences in flight ability compared to wild-type. Indeed, the indirect flight muscle myofibrils of these mutants are assembled normally. There aren't any significant differences between control and mutant flies in major structural parameters such as sarcomere length, thick filament number per myofibril cross-sectional area, and percentage of myofibril area per muscle cross-sectional area. Mutant flies exhibit a 1.4-2.7% increase in myofibril cross-sectional area, although the number of thick filaments per fiber is unchanged.