To decipher the role of mitochondrial Ca2+ signaling in metastatic potential, we collected the mRNA levels of MCU and related proteins (MCUb, MICU1‐3, and EMRE) from the TCGA breast cancer dataset (http://tcga-data.nci.nih.gov/docs/publications/brca_2012/) (Koboldt et al, 2012). The gene discussed is MCUB; the disease is breast carcinoma.