摘要
The phiLosophy of Yin （阴） and Yang （阳） formed in ancient China describes a subtle, complementary, and sometimes intimate relationship between two opposites. This thousands of years old phil- osophy is, however, perfectly suited to describe the relationship between p53 and MDM2, whose genes evolved hundreds of millions of years ago. p53 and MDM2 are found in both （some） invertebrate and （all） vertebrate organisms, and mutually live with and almost always depend on each other in most multi-cellular organisms, including humans.
