LoxP sites were inserted into intron 10 and intron 13. Cre-mediated recombination removed exons 11 through 13. The predicted truncated product mimicks the protein involved in Amish nemaline myopathy. A FRT-flanked neomycin resistance cassette was inserted into intron 10. Western blot analysis confirmed the absence of protein expression in the soleus muscle. (J:219907)