TGFB1 and breast carcinoma: Finally, human muscle samples taken from patients with breast cancer and lung cancer with bone metastases had oxidation of RyR1 and loss of calstabin1, validating the clinical significance of these data.121 Thus, TGFβ released from the tumor‐bone microenvironment promotes oxidation of RyR1 and contributes to cancer‐associated skeletal muscle weakness.