To the Editor: Dr. Dwork and colleagues raise several interesting issues. We emphasized that our main conclusion was merely that the decrease in spinophilin mRNA provides a further indication that the site of molecular alterations in synapses in schizophrenia and mood disorders includes dendrites as well as presynaptic terminals. We also suggested, parsimoniously, that the reduction is probably related to the decreases in spine density, which the correspondents and others have clearly demonstrated. Given what is known of the functions of spinophilin, as outlined in their letter, we agree that the reduction in its mRNA is more likely to be a consequence than a cause of the lower spine density (i.e., fewer spines require synthesis of less spinophilin), as we pointed out in our article (p. 1862). The fact that the percentage decrement in spine density is much greater than the reduction of spinophilin mRNA can be explained, as Dr. Dwork and colleagues note, by the fact that changes in transcript abundance are often less than those of the encoded protein and that the subcellular difference in the targeting of proteins may exist. Along similar lines, the lack of change in microtubule-associated protein 2 mRNA that we find may signify that any putative changes in microtubule-associated protein 2 are translational or posttranslational in origin.