Proteasome activity is essential for cell homeostasis and is also controlling (by ubiquitination of key proteins) various selected process in cancer cells, e.g., cell cycle control (cyclins, cdk inhibitors), oncogenic transformation (N-myc, c-jun), tumor suppression (p53), apoptosis (Bax) and regulation of transcription factors (NFκB) [2–4]. The gene discussed is TP53; the disease is cancer.