Upon the onset of X-inactivation, the future Xi ceases to express Tsix RNA (and increases Xist expression), whereas Xa continues to express Tsix for several days.
Despois do comezo da inactivación X, o futuro Xi deixa de expresar o ARN Tsix (e incrementa a expresión de Xist), mentres que o Xa continúa expresando Tsix durante varios días.