MICS1 was clearly coprecipitated with cytochrome c-3FLAG and the amount was DSP concentration-dependent (Figure 6A). Together with the finding that overexpression of exogenous MICS1 delayed the apoptotic release of cytochrome c in normal-serum level medium (Figure 4A), these results suggest that MICS1 helps to retain cytochrome c in the inner membrane, apart from the morphological changes.