Answer:
Cyclins are proteins that bind to kinases (i.e., cyclin-dependent kinases), by acting as their cofactors. The cyclin-dependent kinases play critical biological functions such as, for example, the regulation of the cell cycle, mRNA processing, etc. The inhibitors of cyclin-dependent kinases are able to alter the cell cycle progression and thereby inhibit cell death (apoptosis), which is common in cancer cells .