NAP125, also known as NCKAP1 (NCK-associated protein 1), p125Nap1 or membrane-associated protein HEM-2, is a 1,128 amino acid single pass membrane protein that exists as two alternatively spliced isoforms and belongs to the HEM-1/HEM-2 family. While widely expressed, NAP125 is found at highest levels in heart, brain and skeletal muscle where it regulates Rac-dependent actin remodeling as part of a lamellipodial complex with WAVE2, Abi-1 and CYFIP1. NAP125 localizes to the cytoplasmic side of lamellipodium membrane and is encoded by a gene that maps to human chromosome 2q32.1 and mouse chromosome 2 C3. NAP125 expression is markedly reduced in Alzheimer disease (AD)-affected brains, suggesting a possible role in the disease.