Titin, the largest protein in the human body, is well known as a molecular 
spring in muscle cells and scaffold protein aiding myofibrillar assembly. 
However, recent evidence has established another important role for titin: that 
of a regulatory node integrating, and perhaps coordinating, diverse signaling 
pathways, particularly in cardiomyocytes. We review key findings within this 
emerging field, including those related to phosphorylation of the titin springs, 
and also discuss how titin participates in hypertrophic gene regulation and 
protein quality control.