A) Fura recordings in skin fibroblasts at baseline and 16 h after serum/PDGF-induced cell cycle progression. n= 8 biological replicates for WT 16 h, 7 for MCU−/− 16 h, 6 for all other conditions. B) Ca2+ Green 5N assay in skin fibroblasts at baseline and 16 h after serum/PDGF-induced cell cycle progression. Treatment with digitonin (Dig, 0.005%, arrow), Ca2+ (1 μM, asterisks). n = 2 independent experiments. C) Oxygen consumption (OCR) by Clark electrode in skin fibroblasts at baseline and 16 h after PDGF-induced cell cycle progression. n= 7 biological replicates for WT 16 h, 6 for MCU−/− 16 h, 5 for all other conditions. D) Immunoblots for EMRE, MICU-1, MCUB, and NCLX at baseline and 16 h after serum/PDGF-induced cell cycle progression. E) Quantification of EMRE levels as in D). n = 6 independent experiments. F) Quantification of MICU-1 levels in D). n = 5 independent experiments. G) Quantification of MCUB levels as in D). n = 6 independent experiments. H) Quantification of NCLX levels as in D). n = 4 independent experiments. * p<0.05, ** p < 0.01 by Kruskal-Wallis test.