Figure 4

Heterotrimeric Gi-protein-dependent signalling drives proliferation of CRC cell lines. A 10 μM lysophosphatidic acid (LPA), 100 μM Isoproterenol, 100 ng/ml PTX and 10 nM PGE2 were administered alone or in combination to serum-starved HT-29 cells. 96 h later [³H]-thymidine incorporation into cellular DNA was scored as described before. Data are mean ± S.E.M. of counts per minute (normalized values to average of control) of tetraplicates. B Effect of PTX and LPA on PKA substrate phosphorylation. Serum-deprived HT-29 cells were treated as indicated in the legend and PKA-substrate phosphorylation was assessed as before.