AGFG1 and embryonal carcinoma: However, while the expression and function of Rab family small GTPases have been clarified using various types of cells, there has been only one report on the expression and function of Rab proteins in chondrocytes, which showed that Rab23 regulates chondrocyte differentiation in embryonal carcinoma-derived chondrogenic cell line, ATDC5 cells [17].