CD99P1 and nicotine dependence: Interestingly, GSEA revealed that RPL3L, PLEK2, PYCRL, CD99P1, LOC100133130, MELK, LINC01101, and DLG3-AS1 were mainly involved in nicotine addiction, diabetes, protein export, taste transduction, fatty acid degradation, propanoate metabolism, endocrine and other factor-regulated calcium reabsorption, GABAergic synapse, steroid biosynthesis, synaptic vesicle cycle, carbohydrate digestion and absorption, proteasome, and asthma.