VCP (valosin-containing protein), also known as p97, TERA, ALS14, IBMPFD, HEL-220, IBMPFD1, or HEL-S-70, is a member of a protein family that includes putative ATP-binding proteins involved in vesicle transport and fusion, 26S proteasome function, and assembly of peroxisomes. VCP is a structural protein that associates with clathrin and heat-shock protein Hsc70, to form a complex. It has been implicated in a number of cellular events that are regulated during mitosis, including homotypic membrane fusion, spindle pole body function, and ubiquitin-dependent protein degradation. In sperm this intra-acrosomal protein can be used as a marker for evaluation of the physiological state of sperm cells as well as for selection of a suitable method of fertilization in the laboratories of assisted reproduction.