Because SYK, which has been reported as an AD target, acts as a downstream kinase of Fyn signaling and as an upstream kinase of IKK in several cell types [46,47], we further tested whether CA-PH inhibits SYK activity by examination of the phosphorylation level of SYK at tyrosine residues 525 and 526 [48,49,50]. This evidence concerns the gene SYK and Alzheimer disease.