Abstract: The present invention provides a compound of formula I: wherein A, D, R1, and R2 are as defined in the specification; or a salt or a detectably labeled derivative thereof. The invention also provides methods of using the compound of formula I or a salt or a detectably labeled derivative thereof for promoting the proliferation of hemopoietic progenitor cells without cell differentiation.

Abstract: The present invention describes a family of photolabile caged nucleotides, including cyclic nucleotides. The compounds of the present invention are caged analogs and derivatives of NAD.sup.+, NADH, NADP, NADPH, NAADP and cADPR. The photolysis of the present compounds allows the release of the free nucleotide in vivo or in vitro with precise spatial and temporal control. The compounds are useful for the photolytic generation of free nucleotides in aqueous samples, for example, in the study of calcium mobilization in cells and cell homogenates.

Abstract: Cyclic ADP-ribose (cADPR) analogs block cADPR from releasing Ca.sup.+2, and also inhibit cADPR from potentiating Ca.sup.+2 release induced by either divalent cations or by caffeine. 8-amino-cADPR and two other 8-substituted analogs were also synthesized. Both 8-Br- and 8-azido-cADPR were also antagonists, although with less potency than 8-amino-cADPR. These results show that alterations at the 8-position of the adenine group do not inhibit cADPR from binding to its receptor but do eliminate the ability of the metabolite to activate the Ca.sup.+2 release mechanism.