Interaction of TTP and PARP-14 with TF mRNA is interdependent. (A) Western blots of proteins isolated with streptavidin beads from lysates of LPS-treated WT, Ttp^−/−, and Parp14^−/− macrophages (1 µg/mL, 2 hours) incubated with sense (+) or anti-sense (-) biotinylated murine TF 3′UTR. TF 3′UTR did not pull down TTP in the absence of PARP-14 or PARP-14 in the absence of TTP. (B) Western blots of proteins immunoprecipitated from LPS-stimulated WT lysates with anti-TTP antibody (T) or goat IgG control (C). Coimmunoprecipitation of PARP-14 was abolished by prior treatment of the lysate with ribonuclease-postitive (RNase⁺), showing that the association of PARP-14 with TTP was dependent on RNA.