Generates phosphatidylinositol 3-phosphate (PtdIns3P) and phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2) that act as second messengers (PubMed:9514948). May play a role in SDF1A-stimulated chemotaxis. a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3,4-bisphosphate) + ADP + H(+) a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3-phosphate) + ADP + H(+) Expressed predominantly in liver. Also found in kidney, lung and lymphoid tissue. Down-regulated in BeF3 cells expressing the BCR-ABL oncogene p185. Belongs to the PI3/PI4-kinase family.