PPIA and Alzheimer disease: Notably, pathologically relevant markers of AD in M4 (YWHAZ, YWHAH, PPIA, ENO1), including members of the 14‐3‐3 family, were not as vulnerable to the effects of plasma addition to AD‐like CSF, potentially due to their enrichment in exosomes, which could hypothetically confer an additional barrier to proteolytic digestion.52, 55