The synthesis and secretion of serum albumin in Morris hepatomas 5123tc and 9121.

In vivo, Morris hepatomas 5123tc and 9121 do not secrete serum proteins into the bloodstream. However, they synthesize albumin, at a reduced rate, if compared with liver. The produced albumin accumulates, leading to an enlargement of the Golgi apparatus and the appearance of intracellular vesicles. The proportion and the absolute amount of albumin found within the hepatoma cells is increased compared with liver. As described recently for liver in vivo and for hepatocyte suspensions, albumin is synthesized also in hepatoma cells via a precursor protein. Hepatoma cells in culture secrete albumin into the medium. However, albumin accumulates in the cells with time in culture, indicating again a limited secretory capacity of the hepatoma cell.