Abstract: There is disclosed an isolated cDNA sequence (SEQ ID NO:1) encoding a P4.33 polypeptide and comprising a coding region (SEQ ID NO:2) of the sequence described in SEQ ID NO:1, or a sequence having at least 90% homology with the coding region of SEQ ID NO:1. The P4.33 polypeptide functions as a specific cell-surface receptor for IGFBP-3, and undergoes nuclear translocation in combination with IGFBP-3. IGFBP-3 and P4.33 (IGFBP-3R) cooperatively suppress DNA synthesis and cell growth, and induce caspase activation and apoptosis in cancer cells, indicating that P4.33 is an important mediator of IGF-independent growth inhibitory actions of IGFBP-3. The P4.33:IGFBP-3 system of the present invention can be used, inter alia, in screening and diagnostic assays, and for therapeutic methods for cancer treatment and tumor suppression.