Undifferentiated embryonal carcinoma cells also express genes involved in the stimulation, and the inhibition of cell proliferation and in the direct malignant growth promotion, such as Transforming Growth Factor-α (TGF-α) and Fibroblast Growth Factor-4 (FGF-4) respectively, but also retain cellular malignant features through the expression of Teratocarcinoma-Derived Growth Factor-1 (TDGF-1), also known as Cripto-1. This evidence concerns the gene FGF4 and embryonal carcinoma.