CD4 and systemic lupus erythematosus: As a result of reduced ERK activity in lupus CD4+ T-cells, expression of Dnmt 1 is reduced, DNA hypomethylation ensues and the CD4+ T-cells become autoreactive (see Figure 1 for the proposed molecular pathways linking oxidative stress, suppression of the PKC and ERK pathways and reduction of Dnmt1 with lupus development).