Expression of differentiated functions in hepatoma cell hybrids: high frequency of induction of mouse albumin production in rat hepatoma-mouse lymphoblast hybrids.

We have studied the production of serum albumin by somatic hybrids between well-differentiated 2s and 1s rat hepatoma cells (Faza), which produce serum albumin, and sub-diploid mouse leukemic lymphoblasts (Lc), which do not produce albumin. We determined the rat or mouse origin of the albumin by double immunodiffusion, using immuno-adsorbed noncrossreacting antisera. Each of 12 karyologically identified 2s hybrid clones (Lc2F) produces both rat and mouse albumin. Moreover, unlike 1s hybrids reported previously, eight of nine 1s hybrids (LcF) also produce mouse albumin; six of them produce rat albumin as well. One clone from the 1s cross produces only rat albumin.