HSP90 is a molecular chaperone that stabilizes and activates over 200 proteins, many essential for cell signaling and stress responses. Cancer cells are highly dependent on HSP90 for survival, as it helps maintain oncogene function. Recent advances have clarified the complex regulation of HSP90 and its role in both cancer and normal physiology. HSP90 functions through a dynamic complex involving HSP70 and co-chaperones, which modulate client protein interactions and stability. HSP90 is involved in various cellular processes, including transcription, chromatin remodeling, and DNA repair. Its regulation is influenced by post-translational modifications such as phosphorylation, acetylation, and S-nitrosylation, which affect its activity and client protein interactions. HSP90 inhibitors have shown promise in clinical trials, with several compounds currently under evaluation. However, the effectiveness of these inhibitors can vary depending on the cancer type and the expression of co-chaperones. HSP90 inhibitors may also impact normal cellular functions, and their use requires careful consideration of potential side effects. The development of HSP90-targeted therapies is an active area of research, with ongoing efforts to improve drug efficacy and reduce resistance.HSP90 is a molecular chaperone that stabilizes and activates over 200 proteins, many essential for cell signaling and stress responses. Cancer cells are highly dependent on HSP90 for survival, as it helps maintain oncogene function. Recent advances have clarified the complex regulation of HSP90 and its role in both cancer and normal physiology. HSP90 functions through a dynamic complex involving HSP70 and co-chaperones, which modulate client protein interactions and stability. HSP90 is involved in various cellular processes, including transcription, chromatin remodeling, and DNA repair. Its regulation is influenced by post-translational modifications such as phosphorylation, acetylation, and S-nitrosylation, which affect its activity and client protein interactions. HSP90 inhibitors have shown promise in clinical trials, with several compounds currently under evaluation. However, the effectiveness of these inhibitors can vary depending on the cancer type and the expression of co-chaperones. HSP90 inhibitors may also impact normal cellular functions, and their use requires careful consideration of potential side effects. The development of HSP90-targeted therapies is an active area of research, with ongoing efforts to improve drug efficacy and reduce resistance.