VCP and cancer: Together, these data show that: (1) the loss of p97 activity impairs cancer growth and the CSC population of MDA-MB-231 cells both in vitro and in vivo; (2) blocking ERAD by Eer I produces almost identical phenotypes as global inhibition of p97’s ATPase activity by NMS-873; (3) the breast CSCs are much more sensitive to the inhibition of p97 than non-CSC cells.