The effect of dibutyryl adenosine cyclic 3': 5' monophosphate (db-cAMP) on growth, adhesion and motile properties of glucosamine-requiring mutant, G72-8 derived from Chinese hamster lung cells was studied. The properties of the mutant cells, which was characterized by a round morphology and a decreased adhesion, was further emphasized when treated with mannosamine. The mutant cells become spindle shape and look similar to parent cells when treated with db-cAMP, whereas the adhesiveness remains decreased. Further, when the mutant cells cultured with mannosamine was treated with db-cAMP, their cell behaviors showed no significant change in spite of recognizable morphological reversion. The mutant cells showed a slight decrease in the content of cyclic AMP when compared to the parent cells, but no significant differences between the mutant cells grown in presence and absence of N-acetylglucosamine were observed. On the other hand, N-acetylglucosamine restored to normal their cell behaviors of the mutant. Our results indicate that at least a defect in adhesion response for the change in cell surface components (glycoproteins and/or glycolipids).