PAX3 and rhabdomyosarcoma: In addition to its suppressive effect on type I myofibers, SKM-specific ablation of FOXO1 also increased the type II myofiber phenotype [285]; as mentioned in Section 3.7.1, rhabdomyosarcoma proliferation is inhibited by a PAX3-FOXO1 fusion protein [284]; accordingly, a decreased amount of type II myofibers was associated with a pro-tumorigenic effect, raising the possibility that the reverse may also be true.