Signaling pathways are complex networks of molecules that communicate signals within and between cells. These pathways help cells respond to various stimuli, such as hormones, nutrients, or environmental changes. When a signal is received, it triggers a series of biochemical reactions, often involving proteins, that ultimately lead to a specific cellular response, like growth, division, or apoptosis (cell death). These pathways are crucial for maintaining homeostasis and regulating various biological processes. For example, the insulin signaling pathway helps control blood sugar levels, while the MAPK pathway is involved in cell growth and differentiation. Disruptions in these pathways can lead to diseases, including cancer and diabetes.