Although the size of the S100 protein is relatively small (8-12 KDA) and the structure is simple, it can regulate various cell processes such as cell growth and movement, cell cycle process, transcription and differentiation. Each S100 monomer has two EF hand -based lines, which can combine up to two calcium molecules. S100A1 expresses high in myocardial and skeletal muscles, and plays a main role in regulating the shrinkage of calcium dependence. S100A1 can be used to distinguish the colorful renal cell carcinoma (CHRCC) and kidney acidic cell tumors.