TPBG and neoplasm: Attempts to detect a physical complex of 5T4 and CXCR4 have been successful in human tumor cells which exhibit higher levels of 5T4 expression and where pulldown and reciprocal western analyses suggest association of some 5T4 and CXCR4 molecules in non-ionic detergent solubilized lysates (Southgate et al unpublished).