Reduced in vivo muscle strength in IT/+ mice. (A) In vivo hanging task determination of upper body strength in WT (n = 13 mice; black bar) and IT/+ (n = 12 mice; gray bar) mice. (Left) Average hanging scores from 10 trials/mouse (refer to Materials and methods for details). (Right) Percentage of hanging task trials in which WT and IT/+ mice successfully escaped to one of the stanchion supports. (B) Average grip strength (five trials/mouse) assayed from WT (n = 8 mice; black bar) and IT/+ (n = 14 mice; gray bar) mice using a digital force gauge (GTX; Dillon) set to record the peak tensile force generated by mice gripping a metal grid while being pulled away until grip fails. *, P < 0.01; †, P < 0.05.