Artificial DNA demethylation up-regulates P-lig expression on effector T cells. Naive transgenic CD4⁺ cells were activated with OVA_323-339 peptide and APCs either with or without cytokine supplement (IL-12, IFN-γ, and αIL-4) as indicated and in the presence or absence of the DNA methylation inhibitor 5-aza-2-deoxycytidine (5 μM) and cell-cycle inhibitor l-mimosine. Data from 1 of 4 similar experiments are shown. Numbers in top right corners indicate the percentage of P-lig–positive cells in culture.