Fig. 5. Integrin clustering and PKA activation are both required to induce cell-cell adhesion. (A) The effect of 10 µM Sp-cAMPS on HT-1080 cell-cell adhesion in the presence of no antibody or 0.3 µg/ml 12G10. (B) The effect of integrin clustering and 10 µM Sp-cAMPS on HT-1080 cell-cell adhesion. CCAI was scored and defined as described in Materials and Methods. Asterisk indicates P<0.01 vs. no treatment. Values shown are mean±s.d. (n=8).