LAMB2 and muscular dystrophy: Staining of skeletal muscles for laminin, a major component of the extracellular matrix, revealed muscular dystrophy in Sil1Gt skeletal muscles, with a loss of the typical polygonal myofiber morphology and a wide range in myofiber diameter, including large, rounded hypertrophic fibers and shrunken, degenerating atrophic fibers (Fig. S2A,B).