Effect of Tat induction on contextual fear-conditioning assessments. No differences were observed in the freezing behavior of Tat−/DOX and Tat+/DOX mice either before or immediately after a conditioning foot shock (indicated by arrow, 3 min after baseline measures). However, there was a significant decrease in freezing behavior observed in mice expressing Tat protein (Tat+/DOX, n = 9) 24 h after foot shock conditioning, as compared to control Tat−/DOX [n = 7; main effect of group: F(2,42) = 7.44, *p < 0.01] group. Data are mean ± SEM. DOX: doxycycline.