A culture system was developed which permitted the differentiation of chicken lens epithelial cells to lentoid bodies which contained several cell layers, accumulated high levels of delta-crystallin, and produced extensive gap junctions. This differentiation process was prevented when the cells were infected with a temperature-sensitive src mutant of Rous sarcoma virus and maintained at the permissive temperature. These transformed cells continued to proliferate and also synthesized the major lens gap junction protein, MP28, at near-normal rates. However, this MP28 was not assembled to produce gap junctions. Cultures shifted to the nonpermissive temperature formed lentoid bodies similar to those in uninfected lens cultures, including the establishment of gap junctions containing MP28.