CDK5 and gastric cancer: Majority of studies supported that CDK5 might have a role in promotion of multistep process of tumor formation and progression, including transformation, proliferation, angiogenesis, invasion and metastasis.17, 18 On the contrary, Cao et al.19 found that CDK5 was decreased in gastric cancer and overexpression of CDK5 could inhibit gastric tumorigenesis.