LPAR4 and hereditary elliptocytosis: On the other hand, the mRNA expression of LPAR1, lysophosphatidic acid receptor 4 (LPAR4), and AQP4 were significantly decreased, while lysophosphatidic acid receptor 5 (LPAR5) was considerably increased in the cerebral cortex of HE mice compared to the sham group (Fig. 3c).