Most animal cells exhibit anchorage dependence, which means that in order to divide

Most animal cells also exhibit anchorage dependence. To divide, they must be attached to a substratum, such as the inside of a culture jar or the extracellular matrix of a tissue. Experiments suggest that like cell density, anchorage is signaled to the cell cycle control system via pathways involving plasma membrane proteins and elements of cytoskeleton linked to them.