In order to respond to various external or internal environmental stimuli, organisms develop complex cell signaling pathways consisting of receptors, kinase cascades, and other regulatory proteins. Recently, JMCB has published a number of research articles uncovering new members or regulating mechanisms of various cell signaling pathways. In this issue, more research works provide new information for understanding the molecular mechanisms and functions of TGF-β signaling as well as other cell signaling pathways for pathological responses.