a.The studies of hormons such as progesterone, testosterone and 21-OH progesterone as stressors of primitive eukariotic organism represent the new contribution to understanding the effects of human hormons on these organisms, since until now there were not studied. Moreover, the first genes encoding steroidal inducible cytosolic Hsp70s from Zygomyces fungi were isolated, analysed and their expression was studied. The results obtained are important from phylogenetic poin of view for primitive eukariotic organisms. The identification of progesterone receptors coupled to G proteins in fungus Rhizopus nigricans is the first report of such signaling pathway in the fungal kingdom. b. The studies of genetic polymorphism of human cytochromes P450 contributed to the understanding of population genetics of a large number of genes having important role in drug and carcinogen metabolism. The major advantage of knowing the frequency distribution of genetic polymorphisms in a given population is the ability to predict the efficacy and side effects of drugs metabolised by the polymorphic enzymes. This enables the design and selection of drugs, that are most efficient and have the lowest risk of unwanted side effects in a given population. The studies of genetic polymorphisms influencing carcinogen activation and detoxification contributed to our understanding of the earliest steps in the complex proces of environmental carcinogenesis. The results of these studies were included in the Collaborative International Project on Genetic Susceptibility to Environmental Carcinogenesis.