- Embryonal carcinoma cells express Qa and Tla class I genes of the major histocompatibility complex. Ostrand-Rosenberg, S., Nickerson, D.A., Clements, V.K., Garcia, E.P., Lamouse-Smith, E., Hood, L., Stroynowski, I. Proc. Natl. Acad. Sci. U.S.A. (1989)