MAP2K7 and systemic lupus erythematosus: Interestingly, the phosphorylation of MEK (0.76 ± 0.25 vs. 1.18 ± 0.30, P = 0.04) and ERK (0.37 ± 0.19 vs. 1.27 ± 0.35, P = 0.0001) protein increased in PBMC on the third day when PBMC from SLE patients and BM-MSC from healthy volunteers were mixed cultured at a 15 : 1 ratio compared with the no-coculture group (Figures 2(a) and 2(c)).