Abstract: ObjectiveKAI1 closely correlates with pancreatic cancer metastasis.There might be some factors that protect the cells from a proliferation inhibition by KAI1 in the solid tumors’ microenvironment.Hypoxia and ischemia are the main characteristics of the microenvironment within solid tumors.Whether they affect the KAI1 inhibitory effects on cell proliferation is still unclear.Methods MiaPaCa-2 human pancreatic cancer cells do not express KAI1 protein.However,after being infected with Ad5-KAI1,they expressed KAI1 protein.cultured them under hypoxic and serum-free conditions to simulate the solid tumor hypoxic-ischemic microenvironment.The cells were divided into the control,hypoxic, serum-free,and hypoxic with serum-free groups.The proliferation and apoptosis were observed by CCK8 and Annexin V-FITC/PI,respectively.We, hen observed whether the hypoxic and serum-free conditions could change the effect of KAI1 on cell survival.Results Hypoxia and serum-free media effectively reduced the apoptosis and proliferation inhibition caused by KAI1 and was beneficial to the cell survival.Conclusions Serum free media and hypoxia protected the MiaPaCa-2 cells from a KAI1-induced apoptosis and proliferation inhibition.