Peptidoglycan–polysaccharide (PG-PS)-induced increase in intracellular calcium concentration ([Ca2+]i) is inhibited in CD14 knockout cells. The levels of [Ca2+]i in spleen macrophages were evaluated by using fura-2, a fluorescent [Ca2+] indicator. (a) Kinetics of PG-PS-induced [Ca2+]i (average from six to eight cells). Representative data from two experiments are shown. (b) The average maximal increase in [Ca2+]i shown as a function of PG-PS concentration. Data represent means ± standard error of the mean for 12–34 cells from two independent experiments. The significance of the difference between the groups was calculated using one-way analysis of variance with Scheffe's post-hoc test. *P < 0.05 versus wild-type.