A method for restoring gap junctional intercellular communication (GJIC) in the cells of a mammal, including humans. The method includes administering to mammals who have been determined to have a mutation in the ras gene a phytosterol to restore GJIC. The phytosterol can be .beta.-sitosterol, stigmasterol, or mixtures of these phytosterols. Administering the phytosterol compound both restores gap junctional intercellular communication (GJIC) and inhibits anchorage independent growth of mammalian cells which have a mutation in the ras gene.