Fig. 4

Tiam1 binds nonprenylated Rac1 and supports GTP loading and Il-1β production. a Left, immunoprecipitation (IP) of Rac1 in BM macrophage lysates followed by western blots for Tiam1. Direct western blots were performed on the same lysates (Input) to quantify total Tiam1 and Rac1 levels. Middle and right, levels of Rac1-bound Tiam1 was determined by densitometry of IP-western blots (n = 3/genotype). Actin was the loading control. b Western blot showing levels of GTP-bound Rac1 in lysates of BM macrophages pre-incubated for 24 h with scrambled or Tiam1-targeted siRNAs. Direct western blots were performed on the same lysates (Input) to quantify total Tiam1 and Rac1 levels. c Concentration of Il-1β, 8 h after LPS stimulation, in medium of BM macrophages pre-incubated for 24 h with scrambled or Tiam1-targeted siRNAs (n = 2 genotype). d Left, IP of Tiam1 followed by western blot for Iqgap1. Right, IP of Iqgap1 followed by western blot for Tiam1. Direct western blots were performed on the same lysates (Input) to quantify total Iqgap1, Tiam1, and Actin levels. Error bars represent s.e.m. Significance between groups were calculated with two tailed Student’s t test. *P < 0.05