Revising the notion that CAIII expression in skeletal muscle was specific to type I slow-twitch muscle fibers (Shima, 1984; Vaananen et al., 1985; Zheng et al., 1992; Sly and Hu, 1995), we demonstrated that its expression in soleus muscle remains when the slow fiber content was diminished due to the loss of slow TnT in a transgenic mouse model of TNNT1 nemaline myopathy (Figure 11). The gene discussed is TNNT1; the disease is nemaline myopathy.