sentence: In mammals , three tissue-specific TnI paralogs are found : TnI1 in slow-skeletal muscle ( tnnI1 , ssTnI ) , TnI2 in fast-skeletal muscle ( tnnI2 , fsTnI ) , and TnI3 in cardiac muscle ( tnnI3 , cTnI ) ( reviewed in Shaffer and Gillis 2010 ) .