Answer:
The cells need to have adhered to or to come in contact with the other layer of cells, this phenomenon is termed as anchorage dependence. The cells can get connected with the extracellular matrix, with other cells, or tissue culture plastics through proteins. In any way, various kinds of cells need some kind of anchorage in order to thrive.
However, if a mutation permits the cell to overlook anchorage dependency, then the cells might proliferate and travel off. This generally takes place when cancer goes through metastasis and affects the entire body.