Pax3-Foxo1 fusion RNA is not detected in mouse muscle differentiation/regeneration systems. (a) Mouse myoblast cell line C2C12 were induced to differentiate along a skeletal muscle lineage. RNA was extracted from samples harvested from 4 to 96 hours. (b) Bone marrow-derived mesenchymal stem cells, D1-MSCs, were induced to differentiate along a skeletal muscle lineage. RNA was extracted from samples harvested every other day from day 2 to day 22. (c) Mouse embryonic stem cell line, E14, was induced to differentiate along a skeletal muscle lineage. RNA was extracted from samples harvested from day 1 to day 8. (d) Pax3–Foxo1 RNA is absent in mouse fetal muscle samples. RNAs were extracted from fetal (muscle) samples harvested every other day from embryonic day 8 to day 20. (e) A time course of muscle regeneration was induced in the tibialis anterior (TA) muscles by cardiotoxin (CTX) injection. RNA was extracted from the muscle samples collected from day 1 to day 7. In all above, RNAs from the rhabdomyosarcoma cell line RH30 or mouse myoblast cell line C2C12 were used as controls. Pax3–Foxo1, MyoD, MyoG, Myh1, and Gapdh RNAs were assessed by RT-PCR. Lower panels are immuostaining of EDU on CTX or PBS treated muscle slices.