ABSTRACT
In 1909 Stepp first described a fat-soluble material which proved essential for life. Stepp carried out experiments on extracted "fat-free" diets and was able to show that the extracted food did not allow laboratory mice to survive unless an extract from egg yolk was added to the diet. The purpose of the communication is to review the relationship between retinoids and mammary gland tumorigenesis in rats, mice, and humans and to examine mechanism(s) by which retinoids might influence this neoplastic process. The first direct evidence of a significant inhibitory effect of high levels of dietary retinoids on the development of mammary tumors in experimental animals was reported by Moon et al. Although there have been a number of reports documenting the chemopreventive activity of a variety of dietary retinoids in rat mammary gland tumorigenesis, fewer laboratories have examined this activity in mice.
