ZEB1 and myalgic encephalomeyelitis/chronic fatigue syndrome: While EMX2 could not be detected in PBMCs (data not shown), ZEB1 level was found to have a mild but significant elevation in ME/CFS PBMCs as compared with controls (ME/CFS median ΔCT vs. control median ΔCT:7.60 vs. 7.82, p < 0.05, Fig. 4a).