The TF 3′UTR distal ARE regulates luciferase mRNA. Luciferase reporter constructs containing 3′ UTR inserts derived from the TF mRNA sequence were transfected into RAW 264.7 cells, and luciferase activity was then assayed after 16 hours. (A) Shows the effects on luciferase activity of full-length TF 3′ UTR compared with a panel of constructs with 7 guanine substitutions in the conserved ARE in the ARE4 segment (= ARE*), in the miR 19a/19b binding site (= miR-A*) or the miR 20a/20b/106b binding site (= miR-B*), alone or in combination. ARE mutation significantly increased luciferase activity, and this was augmented by the substitutions in miR-A and miR-B. P values refer to comparisons with unmutated 3′ UTR. (B) Shows the destabilizing effect of inserting the isolated ARE4 segment of the TF 3′UTR into the luciferase reporter construct, relative to the luciferase coding region with no 3′ UTR insert. Also shown is the significant rescue of luciferase activity by the 7 guanine substitution (as in ARE* in [A]). Data are mean + SEM of 4 experiments, analyzed by one-way analysis of variance. *P < .05; ***P < .001.