PITPNM1 encodes a phosphatidylinositol transfer protein that catalyzes non-vesicular transport of phosphatidylinositol between cellular membranes, with binding affinity ordered as phosphatidylinositol > phosphatidic acid > phosphatidylcholine. The protein is essential for maintaining organellar architecture and function: it regulates Rho-family GTPase activity to control cytoskeletal remodeling, is necessary for cytokinesis completion, maintains diacylglycerol homeostasis in the Golgi, and is required for protein export from the endoplasmic reticulum and Golgi apparatus. PITPNM1 localizes to membrane contact sites where it facilitates phosphoinositide signaling and lipid exchange between organelles. In disease contexts, elevated PITPNM1 expression correlates with poor prognosis in breast cancer, where it enhances epithelial-mesenchymal transition and metastasis through PI3K/AKT and ERK1/2 pathway activation 1. Silencing PITPNM1 in breast cancer cells reduces proliferation and colony formation 2. In endothelial cells, PITPNM1 (also called Nir2) is required for angiogenic tube formation and VEGF-induced signaling 3. Recent evidence also implicates PITPNM1 in chondrogenic differentiation and cartilage homeostasis through PI3K/AKT signaling, with therapeutic potential for osteoarthritis 4. A genome-wide association study identified PITPNM1 as associated with leukocyte telomere length, a marker correlating with mortality 5. Attenuation of PITPNM1 signaling represents a potential therapeutic strategy for breast cancer and other proliferative diseases.