Quantification of cMyBP-C phosphorylation at serines 284 and 304 in cMyBP-C ^+/+ and cMyBP-C ^+/− hiPSC-ECTs. Digital lane view images capillary immunoassay assessing phosphorylation levels of serine 284 (first panel) and serine 304 (third panel). Digital lane view capillary immunoassay images showing total cMyBP-C in the corresponding capillaries are shown in the second and fourth panels. Quantification of serine 284 and serine 304 phosphorylation, normalized to total cMyBP-C are shown as box and whisker plots on the right. n = 4 biological replicates; absolute P values calculated by Student’s unpaired t test with Welch’s correction indicated in each panel.