APOPTOSIS: (CELL SUICIDE) normal cell death
Normal cells do not live for ever. Under certain circumstances cells are programmed to die.
This happens particularly during development, cells that become damaged beyond repair will normally undergo some sort of PROGRAMMED cell death. This is called APOPTOSIS.
CELL ARREST :
Is a induced process. It takes place in G1 phase of cell cycle.
This is carried out experimentally by introducing some INHIBITORS ( see links included).
In case of many medical disease treatments, for example leukaemia, cancers of various organs such inhibitors are used to arrest the cell cycle at G1 and before G2 phase.