Summary
Experiments were described in which mouse L-929 cells were exposed to cAMP and various related cyclic nucleotides. One cyclic nucleotide, 6-MT-PRcP, enhanced IF activity as much as 16 to 32-fold when cells were exposed to a 10-2
M concentration for 4 hr prior to compound removal and addition of IF. Treatment of cells with 8-BrcAMP and 8-MTcAMP resulted in a 4-fold increase, whereas cAMP, DBcAMP, 8-BTcAMP, and 8-CPTcAMP produced a 2-fold increase. The exact nature of the IF enhancement by these cyclic nucleotides is unknown and may not be the same for all the cyclic nucleotides tested. It is possible that exposure to cyclic nucleotides may alter cells such that they behave as cells under limited growth conditions which respond well to IF.
