Figure 5.

Effect of a mutation in Fstl3 and in genes encoding inhibin β-subunits on muscle mass. A, Diagram of Fstl3-targeting strategy. Mice carrying the targeted allele were crossed to EIIa-cre transgenic mice (33) to generate mice in which recombination had occurred between the outside LoxP sites (denoted by triangles), thereby resulting in a mutant allele in which exons 3–5 were completely deleted in the germline. B, Effects of the deletion mutation in Fstl3 either alone or in combination with heterozygous loss of Fst. C, Diagram of InhβC/InhβE-targeting strategy. D, Effect of Inhβ mutations in male mice. In the bar graphs shown in Panels b and d, numbers represent percent increase or decrease in muscle mass relative to wild-type mice and were calculated from the data shown in Table 1. Data from Mstn^+/− mice (21) are shown for comparison. Muscles analyzed were: pectoralis (red), triceps (gray), quadriceps (blue), and gastrocnemius (green). TK, Thymidine kinase.