The ubiquitin-dependent chaperone Cdc48 (cell division cycle 48)/p97 is involved in a variety of degradative and regulatory processes during interphase that help to maintain cellular homoeostasis. The results available so far suggest that its basic activity is to mobilize ubiquitinated substrate proteins from cellular structures or segregate them from binding partners, and then hand them over for degradation or recycling. Several studies in different organisms show that Cdc48/p97 also has critical roles in mitosis. However, many important aspects of these functions and the general perspective have remained unclear.