LAPTM4A is a lysosomal transmembrane protein involved in nucleoside transport and intracellular protein trafficking. The protein localizes to the Golgi apparatus, late endosomes, and lysosomal membranes 1. Mechanistically, LAPTM4A is a short-lived membrane protein subject to ubiquitin-dependent degradation via the ESCRT pathway, utilizing carboxyl-terminal PY motifs to recruit NEDD4-1 for ubiquitination 2. LAPTM4A interacts with organic cation transporter 2 (hOCT2) to regulate its plasma membrane trafficking and cation transport activity 3. In glycosylation, LAPTM4A specifically regulates globotriaosylceramide (Gb3) biosynthesis through its second luminal domain, acting as an activator for Gb3-synthesizing glycosyltransferases 1. Clinically, LAPTM4A demonstrates significant disease relevance. In glioblastoma, elevated LAPTM4A promotes M2 polarization of tumor-associated macrophages, suppressing anti-tumor immunity; LAPTM4A deletion shifts macrophages toward M1 phenotypes and enhances anti-PD-1 therapy efficacy 4. LAPTM4A represents a robust prognostic biomarker in glioma, correlating with poor outcomes and tumor progression 5. In gestational diabetes, LAPTM4A participates in a regulatory axis with circular RNA hsa_circ_0042260 and miR-4782-3p, modulating hyperglycemia-induced cell responses 6. Additionally, LAPTM4A serves as a predictive biomarker for 5-fluorouracil resistance in colorectal cancer 7 and is incorporated into lysosome-related prognostic models for cervical cancer 8.