L1CAM and early-onset autosomal dominant Alzheimer disease: Mullins et al. (2017) found that neural origin plasma exosomes labeled by L1CAM contained higher pSer312-IRS-1 (ineffective insulin signaling) and lower p-panTyr-IRS-1 (effective insulin signaling) in Alzheimer’s disease. Furthermore, they revealed that higher pSer312-IRS-1 levels were positively related to greater brain atrophy in Alzheimer’s disease and p-panTyr-IRS-1 levels had the opposite effect (Mullins et al., 2017). In a word, exosomes will be the most promising bodily fluid biopsy. As shown in Table 2, some potential exosomal biomarkers can be used to track insulin resistance.