P2RY6 and tauopathy: We found that double-transgenic (P2ry6−/−:P301S+/+) mice had the same severe spinal cord pathology as P301S (P2ry6+/+:P301S+/+) mice (Figure S6), which suggests a different mechanism or severity of neurodegeneration in the spinal cord from the brain in this model of tauopathy.