MK3.2 does not bind to p38 MAPK or ERK1. To determine if there are direct interactions between MK3.2 and p38 (A) or ERK1 (B), lysates from HEK cells transfected with either MK3.1-V5 or MK3.2-V5 (1 mg) were incubated with recombinant GSTp38α, GST-p38β, GST-p38δ, GST-p38γ, GST-ERK1 (1 μg) or GST. Co-precipitated MK3.1-V5 or MK3.2-V5 was detected by immunoblotting using anti-V5 antisera.