Increased expressionand accumulation of p53, as well as p16 andp21, can cause cell cycle arrest.67 Thesemolecular factors are also involved in the apoptotic process.68 Particular variations in cell cycle gene expressionhave been observed between CSCs and the tumor cell population thatthey reside in, according to several studies.69,70. The gene discussed is TP53; the disease is neoplasm.