Impaired activation of MAPK family members and NF-κB by LPS in TAK1-deficient B cells. Splenic mature B cells (AA4.1⁻) were isolated from CD19CreTak1^+/+, CD19CreTak1^fl/+, and CD19CreTak1^fl/fl mice. Cells were stimulated with LPS for the indicated times. Whole-cell lysates were subjected to direct Western blot analysis with the indicated antibodies. Data are representative of 2 independent experiments.