Similar levels of mammary cytokines and chemokines were produced 24 h after intramammary infusion of E. coli P4 in C3H/HeN and C3H/HeJ mice. Bars represent mean concentrations per mg total protein and S.E. of TNFα, IL-1β, MIP-2 and KC measured by ELISA in tissue homogenates of E. coli P4 and PBS-infused control glands of 6 mice in two different experiments. *p < 0.05 value compared means between challenged and control glands using Student’s t-test.