A web of ATRA actions. A flow diagram illustrating the interactions discussed in this capsule and the article by Lal et al. ATRA, by as yet unknown mechanisms, activates a number of signaling pathways usually activated by growth factors. These signaling pathways also impact RAR function. Nontranscriptional and transcriptional effects of ATRA converge at one node, the translational inhibitor 4E-BP1, through the RAR target gene PKCδ as well as p70-S6kinase, which was rapidly activated, presumably through non–RAR-mediated effects on the PI3K pathway. The net result is to augment the action of ATRA on transcription, translation, and the cellular outcome of growth and differentiation.