C4B and erythema multiforme: Compared with the non-tubal EM group, the tubal EM group exhibited significantly increased expression of IL6, ORM2, and TNFA (P < 0.0001), C2, C4B, CP, HP, and SAA4 (P < 0.01) and decreased expression of AHSG and MAP2K6 (P < 0.01) in fallopian tube epithelium using ACTB as reference gene (Supplementary Fig. 1A).