In TB patients, the MEK/ERK pathway regulates FoxP3 expression and Treg function. However, MEK inhibition by trametinib not only reduces Treg activation, but also reduces the expression of IFN-γ, TNF-α, and IL-2 expression in antigen-specific effector T cells. This suggests that the MEK/ERK pathway has a dual role in balancing immune activation and regulation (Lieske et al., 2015). The gene discussed is TNF; the disease is tuberculosis.