When exposed to dexamethasone, neuronal cell lines bioengineered to express the human homolog of the protein tau (PC12-htau) showed a greater degree of susceptibility to the neurotoxic actions of Aβ1-42 as well as marked increases in tau hyperphosphorylation at specific epitopes implicated in AD neuropathology. The gene discussed is MAPT; the disease is Alzheimer disease.