MRGPRX2 and contact dermatitis: Peng et al. discovered that thimerosal, a preservative known for inducing contact dermatitis, is capable of inducing mast cell degranulation and increase of calcium concentration in HEK293 cells transfected with either MRGPRX2 or mrgprb2, and that LAD2 cells with a downregulated receptor showed reduced degranulation when exposed to the agent [72].