In cell signaling, inhibitors and agonists regulate cell functions by affecting key nodes within specific signaling pathways. Inhibitors are compounds that can block or reduce the activity of specific targets in the signal transduction process, thereby inhibiting the activation or function of that signaling pathway. For example, tyrosine kinase inhibitors used in cancer treatment can block the signaling pathways necessary for tumor cell growth and survival. Agonists, on the other hand, can enhance or mimic the activity of certain molecules within a signaling pathway, promoting the progression of signal transduction. For example, β-adrenergic receptor agonists used in some heart disease treatments can enhance the heart's pumping function.