Successful cDNA cloning of LTB4 receptor. Utilizing the fact that the binding ability to LTB4 is induced with retinoic acid, a subtraction library of HL-60 cells was prepared, and was screened to find this receptor cDNA. It was expressed in Cos-7 cells and intracellular signal transduction was analyzed. When expressed in CHO cells, it showed a strong migration ability to LTB4.