SMIM22 (small integral membrane protein 22) is a small integral membrane protein whose specific molecular functions remain incompletely characterized. The UniProt database suggests SMIM22 may modulate lipid droplet formation through interaction with SQLE, and Gene Ontology annotations associate it with lipid droplet formation, cell migration, protein binding, actin cytoskeleton organization, cell cycle regulation, and cell proliferation. The primary evidence for SMIM22's biological relevance comes from cancer research contexts. SMIM22 was identified as one of nine overexpressed genes in CD13+CD166- cancer stem-like cells in hepatocellular carcinoma, where its forcible expression maintained tumorigenicity in culture conditions that would otherwise suppress tumor-forming capacity 1. Additionally, SMIM22 was identified as a DNA-methylation-driven gene significantly associated with survival outcomes in lung squamous cell carcinoma, though the study focused primarily on ALDH7A1 2. In prostate cancer, SMIM22 was one of six differentially expressed genes selected for a risk score signature predicting biochemical recurrence after radical prostatectomy, and notably, this association had not been previously reported in prostate cancer literature 3. SMIM22 expression was also detected as part of an lncRNA-mRNA network response to titanium dioxide nanoparticle exposure in hepatocytes 4. These findings suggest SMIM22 plays roles in cancer stem cell maintenance and tumor progression, though direct mechanistic studies are needed to clarify its functions.