F2RL1 and Alzheimer disease: In this study, using PAR1 and PAR2 knockout (KO) mice and a 2,4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity (CHS) model for human AD [26], we demonstrated that APC therapy reduced the severity of CHS in matched wild type (WT) and to a less extent in PAR1KO mice, but not in PAR2KO mice.