Fig. 4

LPS does not stimulate ERK2 activity in peritoneal macrophages isolated from C3H/HeJ mice

Peritoneal macrophages isolated from C3H/HeJ or C3H/HeN mice were cultured overnight in plastic petri dishes in medium containing 0.5% FCS. LPS (250 ng/ml) or PMA (10 ng/ml) was added to each culture, and the cells were lysed in RIPA buffer 1 hr later. ERK2 activity was assessed using an immune complex kinase assay as described in Materials and Methods. The results are expressed as a ratio of the ERK2 activity present in LPS- or PMA-stimulated cells to the ERK2 activity present in unstimulated controls (i.e., fold induction).