Immunohistochemical study of SphK1/SPL expression and Aβ deposits. (a) Double labeling of SphK1 and Aβ in AD brain section from entorhinal cortex. Diffuse and focal deposits are seen in different areas. X200. Inset: Strongly stained neurons (SphK1++, black arrow) and mild stained neurons (SphK1+, white arrow) are clearly distinguishable. X400 (b) Double labeling of SPL and Aβ in AD brain section from entorhinal cortex. A senile plaque is mainly surrounded by strong labeled neurons (SLP++). X400.