EGF and gastric cancer: Our previous results showed that PKG II could inhibit EGF-induced tyrosine 1068 phosphorylation of EGFR in gastric cancer cell line BGC-823 [6], raising the question whether PKG II can inhibit the phosphorylation of other tyrosine sites on EGF/EGFR and thereafter have a wide-range inhibition on EGF/EGFR-induced signal transductions and related biological activities of gastric cancer cells.