 Induction and repression of p15INK4b; however, has been noted in response to a few signaling events such as RAS activation, that also induce INK4/ARF expression.RAS activation might lead to increased INK4/ARF expression potentially through ERK-mediated activation of Ets1/2 to induce p16INK4.A few repressors of INK4a/ARF/INK4b expression have been identified as well.