The present invention relates to a method for treating cancer using p38/JTV-1 and a method for screening pharmaceutical composition for treating cancer. More particularly, this invention relates to the method for treating cancer, which comprises administering the effective amount of p38/JTV-1 protein or a nucleic acid encoding for said protein to the patient and the method for screening a pharmaceutical composition for treating cancer characterized by selecting a substance having an effect on the increase of the activity of the p38/JTV-1 protein and the intracellular level thereof.The method according to the invention can be effectively used to treat cancer through the mechanism of suppressing the proliferation of cancer cells by binding to FBP (FUSE-binding protein) and thereby promoting the ubiquitination of FBP to downregulate c-myc gene, which is a proto-oncogene, and the mechanism of promoting the apoptosis of cells by binding to PDK-1 (phosphoinositide-dependent protein) and thereby inhibiting the phosphorylation of AKT (serine/threonine kinase). Also, p38/JTV-1 can be used as a target for screening of new anticancer agents, by virtue of such regulation mechanisms of p38/JTV-1.