Figure 4.

ATF4 expression is induced by ER stress but not DNA damage. A, Cortical neurons derived from ATF4^−/− mice and wild-type littermates were treated with tunicamycin (3 μg/ml) or camptothecin (10 μm), and ATF4 protein levels were assessed by Western blot. A nonspecific (ns) band was detected in extracts from both wild-type and ATF4-deficient neurons. NT, Nontreated. B, Cortical neurons were untreated or treated with thapsigargin (1 μm) for the indicated times, and ATF4 protein levels were assessed by Western blot.