CREG1 and embryonal carcinoma: Moreover, cellular repressor of E1A-stimulated genes (CREG), a secreted M6P-capped glycoprotein, can cause internalization of IGF-II that is dependent on M6P/IGF2R, leading to delays in cell cycle progression in human embryonic carcinoma (NTERA-2), smooth muscle cells, and NIH3T3 fibroblast cell lines [29–31].