SAPCD2 (suppressor APC domain containing 2) is a cell cycle-related protein that serves dual regulatory functions in mitotic spindle orientation and cancer progression. The protein plays a crucial role in controlling planar mitotic spindle orientation by negatively regulating the localization of GPSM2/LGN at the mitotic apical cortex, likely through competition with NuMA for LGN binding 1. This mechanism is essential for proper cyst morphogenesis in epithelial cultures and controls asymmetric cell divisions in retinal progenitor cells, with SAPCD2 loss leading to randomized spindle orientation and increased terminal asymmetric divisions 1. In cancer contexts, SAPCD2 is consistently overexpressed across multiple tumor types including colorectal 2, pancreatic 3, gastric 4, neuroblastoma 5, breast 6, and lung adenocarcinoma 7. The protein promotes cancer progression through multiple mechanisms: enhancing cell proliferation, migration, and invasion via YAP/TAZ signaling in breast cancer 6, and regulating E2F7 subcellular distribution to affect cell cycle gene expression in neuroblastoma 5. SAPCD2 expression correlates with poor prognosis and advanced tumor stages, making it a potential biomarker and therapeutic target 346.