A) BMSCs were isolated from mouse long bones, cultured and subjected to various assays; B) BMSCs from CypD+/+ and CypD−/− littermates were subjected to calcium retention capacity (CRC) assay which measures sensitivity to MPTP opening after excessive calcium uptake by mitochondria. CypD−/− BMSC mitochondria accumulate more calcium before opening the pore and, thus show higher CRC; C) CRC was calculated and plotted as a fold change of control CypD+/+. CypD−/− BMSCs show significantly higher CRC and, thus lower MPTP opening when compared to CypD+/+ controls; D) C57BL/6J BMSCs treated with the CypD inhibitor, NIM811, show significantly higher CRC and, thus lower MPTP opening when compared to vehicle-treated controls. Data in (B) are Means ± SD (n = 4). Plots in (C) and (D) show actual data points and calculated means. *, p < 0.05, determined by unpaired t-test. See also Supplementary Figure S1.