CAPN2 and Friedreich ataxia: Evidence that αSpII cleavage in FA cells is due to increased μ-calpain activity is demonstrated by studies which show that in FA-A cells after knockdown of μ-calpain by siRNA and damage with MMC or 8-MOP plus UVA light, αSpII levels are restored to normal and damage-induced αSpII nuclear foci are observed (Figure 7) [13, 38, 44, 69].