IRTKS Regulates MDM2-Mediated p53 Ubiquitination Figure 1. IRTKS suppressed p53-induced apoptosis and transactivation activity. (A) IRTKS inhibited cell death triggered by serum starvation. The IRTKS Tet-off HT1080 cells were cultured in serum-free medium in the presence or absence of doxycycline (DOX, 10 ng/ml). The cells PLoS ONE | www.plosone.org 3 August 2011 | Volume 6 | Issue 8 | e23571