TWIST1 and squamous cell carcinoma: In most adult human tissues, Twist1 expression is usually undetectable; however, the overexpression of Twist1 has been reported in tumors of varying origins, such as breast cancer, bladder cancer, glioma, prostate cancer, pancreatic cancer, sarcoma, squamous cell carcinoma, osteosarcoma, and melanoma [15,16,17,18,19].