The aim of this study was to evaluate the expression profile of proteins involved in growing of human non-small cell lung cancer (NSCLC) in athymic nude mice. The expressions of 20 gene products in primary NSCLC of 170 patients were analyzed and the proteins were correlated with the transplantability of the carcinomas in nude mice. There was no relationship between xenotransplantability of human non-small cell lung cancer in nude mice and histology, stage or lymph node involvement. Of the analyzed proliferative factors PCNA, cyclin A, cyclin D, cdk2, cdk4 and cell cycle phases only cyclin D, cdk4 and the cell cycle phases were up-regulated in growing carcinomas. There was also a correlation between the apoptotic indices and the take rate in nude mice. Concerning microvessel density and angiogenic factors only VEGF showed a relation to xenotransplantability. Of the proto-oncogenes and suppressor gene products N-RAS, P53, FOS and JUN revealed a relationship to the take rate of NSCLC, while such a relationship was not found with MYC, ERBB-1 and ERBB-2. In a second step, a hierarchical cluster analysis was carried out. The resulting clusters were correlated with the take rate of the carcinomas in nude mice. The expression of JUN, N-RAS, FOS, cyclin D, and cdk4 were significantly different in both groups with non- overlapping confidence intervals. Thus, the up-regulation of the proteins JUN, N-RAS, FOS, cyclin D and cdk4 predicts the growth of NSCLC in nude mice.