The Gene regulation can occur at any of the step leading fro DNA to protein product. It is tightly controlled in order to express the required level of gene product at specific time, in specific cell type, and in response to complex changes in the environment. Gene expression is also regulated by multiple posttranscriptional mechanism, including splicing of pre-mRNA, controlling mRNA stability, translation regulation, and posttranslational processing. Regulation of gene can occur at any stages in expression of genetic materials. Chromatin remodeling, transcription, splicing and processing, transport, and degradation of mRNA, translation regulation and protein modification regulate the stages of gene regulation. All these forms of regulation affect the degrees to which a gene is expressed.