MR and TLR4 are not essential for MAPK activation and TNF-α production in BMMϕs upon M smegmatis or M avium 724 infection. BMMϕs from WT and either MR^–/– (A-B) or TLR4^–/– (C-D) mice were infected with M smegmatis or M avium 724 and screened for MAPK activation at 1 hour and 9 hours (A,C) and TNF-α production at 24 hours (B,D). (A,C) MAPK activation was detected by probing cell lysates of infected or noninfected (RC) BMMϕs by Western blot for activated ERK1/2 and p38 using phospho-specific Abs as described in “Materials and methods.” Total ERK1/2 and total p38 blots were run to show equal protein loading. (B,D) BMMϕs from WT and KO mice were infected with complement opsonized or nonopsonized mycobacteria; 24 hours later, culture supernates were removed and analyzed by ELISA for TNF-α. Values are expressed as means + SD. Data are representative of 3 separate experiments. Sm and Smeg indicate M smegmatis; Av and Avium, M avium; and RC, noninfected BMMϕs.