Implicated in tumor cell metastasis. May function in protection of the lysosomal membrane from autodigestion, maintenance of the acidic environment of the lysosome, adhesion when expressed on the cell surface (plasma membrane), and inter- and intracellular signal transduction. Protects cells from the toxic effects of methylating mutagens. Defects in LAMP2 are the cause of Danon disease (DAND); also known as glycogen storage disease type 2B (GSD2B). DAND is a lysosomal glycogen storage disease characterized by the clinical triad of cardiomyopathy, vacuolar myopathy and mental retardation. It is often associated with an accumulation of glycogen in muscle and lysosomes. Belongs to the LAMP family. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.