Cells respond to their environment through a complex and interdependent series of signaling pathways that frequently begin at the cell membrane and transduced by proteins present in the cytoplasm and nucleus. The different steps involved in this process are detection of the stimulus on the surface of the cell membrane, transfer of the signal to cytoplasm, transmission of the signal to effector molecule triggering cell’s response in gene transcription. The various signal transduction members include various receptor such as G-protein coupled receptors, serine-threonine and tyrosine kinases, phosphatases, hormones and transcription factors.