Beta carotene is a member of a class of substances called carotenoids. Beta carotene, alpha carotene and beta cryptoxanthin can serve as dietary precursors of retinoids (RA, all-trans retinol or provitamin A). Biological effects of retinoids and expression of RA responsive gene are mediated by different receptors, namely RAR and RXR in homodimeric or heterodimeric form. Expression levels of the retinoic acid receptors are significantly different in neoplastic tissues compared with non-neoplastic tissues for many types of tumors.
Anna Gozdzicka-Jozefiak, Zaklad Wirusologii Molekularnej, Instytut Biologii Eksperymentalnej, Uniwersytet im. Adama Mickiewicza, ul. Miedzychodzka 5, 60-371 Poznan, Poland