An embryonic carcinoma (EC) cell line (P19 cells) is commonly used to model embryonic myogenic progress in vitro (Figure 6A).[45] Therefore, using the P19 cells, we further explored the mechanistic framework underlying the inverse relationship between Hes1/Hey1 and Mef2c during an induced myogenic process. The gene discussed is HEY1; the disease is embryonal carcinoma.