RESUMO
Extract: It was a long time dream of oncologists to find agents which would cause differentiation to normal of neoplastic cells, thus "taming cancer" without harming normal cells. Our group was involved in such attempts for several decades. Here we summarize some of these studies as well as those of other investigators. Regulation of the differentiation of embryonic cells has been the subject of investigation for many decades. It was thought that "original organizers" appear in the upper lip of the gastrula stage of the mammalian embryo which then induces the production of further "sub organizers" and "sub-sub organizers" which are involved in eventually bringing the entire early embryo to a stage of differentiation. In early experiments we found that in tadpole embryos removal of part of the upper lip of the gastula could be substituted by local insertion of gels containing adenosine triphosphate (ATP), adenosine-3-phosphoric acid, or adenosine-5-phosphoric acid.
