AbstractGamma-interferon (γIFN) was found to induce expression of the 150,000 Mrcell surface and the 35,000M, chromatin receptors for nerve growth factor (NGF) in the SW1116 colorectal carcinoma cell line that does not express NGF receptors. In the SW707 colorectal carcinoma cell line that expresses a low level of NGF receptors, ylFN stimulated expression of the cell surface and the nuclear receptors. Induction of NGF receptors in SW1116 cells resulted in internalization and nuclear translocation of125I-NGF. When NGF bound to the chromatin, ribosomal RNA synthesis was inhibited. Two-dimensional gel electrophoresis of [35S]methionine-labeled chromatin proteins indicated significant changes in chromatin protein composition in cells treated and not-treated withγIFN.γIFN effectively stimulated the expression of NGF receptors in two colorectal carcinoma cell lines, but inhibited the expression in melanoma and breast carcinoma cells. It is suggested thatγIFN, by modulating the expression of NGF receptors may affect the NGF-dependent growth of some tumor cell lines.