 the study examined how liver cells respond to growth factors in order to understand the process of liver regeneration. It found that the presence of growth factors causes the liver cells to divide, but only after they have been exposed to a certain amount of the growth factor. This is done through the activation of several proteins, including cyclin-CDK complexes, P21, and RB. Additionally, the study found that the amount of these proteins present in the liver cells determines whether or not they will divide. Finally, the study also found that the presence of a particular type of kinase, CDK2, is necessary for the liver cells to divide. This article was authored by Stephanie Mueller, Jeremy Huard, Katarina Waldau, and others.