TNNI3 and dilated cardiomyopathy: The deconvoluted mass spectra corresponding to cTnI proteoforms enriched from human serum samples revealed that the endogenous cTnI was primarily in its phosphorylated (mono- and bisphosphorylated) state in the two donor samples (Fig. 4b; panels i and ii), whereas drastic decrease of phosphorylated cTnI was detected in the two diseased samples with dilated cardiomyopathy (Fig. 4b; panels iii and iv).