SLC34A2 encodes NaPi-IIb, a sodium-dependent phosphate cotransporter that actively transports phosphate into cells 1. The protein is predominantly expressed in the lung, specifically in the apical membrane of type II alveolar epithelial cells (ATII), and plays a crucial role in phosphate homeostasis 23. Mechanistically, SLC34A2 regulates cellular phosphate levels through sodium-phosphate symporter activity, with its function being critical for maintaining both local and systemic phosphate balance 1. The transporter's activity is regulated through transcriptional, translational, and post-translational mechanisms involving PDZ domain proteins and membrane trafficking 1. In disease contexts, homozygous mutations in SLC34A2 cause pulmonary alveolar microlithiasis (PAM), a rare autosomal recessive disorder characterized by calcium phosphate microlith deposition in lung alveoli 45. Additionally, SLC34A2 functions as a tumor suppressor, being significantly downregulated in various cancers including non-small cell lung cancer and osteosarcoma 263. In cancer cells, SLC34A2 suppresses proliferation, migration, and invasion through regulation of PI3K/AKT and MAPK signaling pathways 63. Clinically, SLC34A2 represents both a diagnostic marker for PAM and a potential therapeutic target in cancer treatment strategies.