Although the 8-pCPT-2′-O-Me-cAMP affinity for EPAC1 was 107-fold greater than that of PKA, the suppression of PKA activity could reverse the inhibition of the tumour growth and angiogenesis mediated by 8-pCPT-2′-O-Me-cAMP in vivo. This evidence concerns the gene RAPGEF3 and neoplasm.