Protective concentrations of IL-6 do not induce tyrosine phosphorylation of ERK-1 or ERK-2. 8226, UCLA #1, and AF-10 cells were treated with or without IL-6 (1,000 U/mL) for 15 minutes and extracts were immunoprecipitated with an antiphosphotyrosine antibody (IP:αPTY). Immunoprecipitates were then blotted with anti-ERK antibodies (anti-MAPK, upper blot) and with an antiphosphotyrosine antibody (αPTY, lower blot).