MDM2 and soft tissue sarcoma: It has also been reported that the mdm4/mdm2 heterodimers are upregulated not only in the brain and nerve tumor tissues, breast cancer, soft tissue sarcomas, type 1 diabetes, and systemic lupus erythematosus (21–23), but also in the parathyroid glands of patients with renal secondary hyperparathyroidism (24).