Elsevier Inc. nicotinamide adenine dinucleotide biosynthetic pathway cyclic ADP-ribose Bst1 Cd38 NAD+ ---> target ribosylation MAR/PAR erasers MAR/PAR readers NAD+ ---> target deacetylation sirtuins ADP-ribosylation pathway, cyclic ribosylation ADP-ribosylation pathway, mono and poly-ribosylation sirtuin mediated pathway MAR/PAR writers (PARPs) NAD+ ---> cyclic ADP-ribose nicotinamide adenine dinucleotide biosynthetic pathway ---> NAD+ target deribosylation NAD+ target ribosylation ---> target deribosylation target ribosylation MAR/PAR readers ---- target ribosylation target deacetylation