SUMF1 and mucopolysaccharidosis: ,24 Immunostaining for lysosomal-associated membrane protein 1 (LAMP1) on brain sections of MPS-IIIA mice injected with AAV9-IDSspSGSH-IRES-SUMF1 showed a significant reduction in the lysosomal compartment enlargement compared with control MPS-IIIA mice (Figure 3A).