An indispensable collection of novel techniques that have proven most useful for studying the physiological properties of p53 both in vitro and in vivo. The techniques provide proven solutions to problems in studying the purification, target identification, gene expression, quantitation, interaction, signaling, transactivation, and transrepression of p53. The methods are also useful for delineating the functions of other proteins that may act as tumor or growth suppressors. Each technique includes step-by-step instructions, troubleshooting notes, a theoretical review, and discussion of associated problems that might arise during the course of investigation.