[Cyclic AMP, the cytoskeleton and control of cell replication. I. Relationship of cyclic AMP, microtubules and density-dependent growth].

CHO cells after being treated by Bt2cAMP (1M), would reverse to the fibroblastoid cell morphologically. The cell body appears spindle, more orientational and polarized. The Bt2cAMP, rendering the cells grow were slowly, did not block them from G1 to S phase. The "contact inhibition" was restored to some degree. The most saturated density of the cells was reduced to 47.4% as compared with the control CHO cells. When CHO cells were treated by Bt2cAMP added with Colcemid (0.05 micrograms/ml), the microtubules (MT) were destroyed. Still, the cells were able to reach the "contact inhibition". The signal of "contact inhibition" may not approach the nucleus via MT.