The cell cycle is controlled by a number of highly conserved proteins,
found in species as diverse as yeast and mammals. The study of these
proteins is a rapidly advancing held that is increasing our understand
ing of normal and abnormal cell division. Disruption of the cell cycle
has been demonstrated in several different types of neoplasm, and the
re is increasing evidence that, in head and neck tumours, there is abe
rrant control of cyclins, cell cycle protein kinases and their inhibit
ors. Because of the phase specificity of some of the control proteins,
antibodies to them are proving to be of value in studying cell kineti
cs of both normal tissues and malignant tumours. (C) 1987 Elsevier Sci
ence Ltd.