Genetic sequences of the novel NSP gene, which encodes neuroendocrine-specific proteins, were isolated from cDNA libraries constructed with mRNA isolated from human lung carcinoma cells. Hybridization analysis of a panel of human × mouse cell hybrids with an 0.8-kb NSP cDNA probe indicated that the human NSP gene is probably located on chromosome 14. Fluorescence in situ hybridization analysis of metaphase chromosomes using overlapping genomic clones of NSP as a probe localized the NSP gene to chromosome region 14q21→q22.