Interestingly, in contrast to Tcf21 lineage-traced cardiac fibroblasts which all differentiated into myofibroblasts expressing Postn in response to injury (Kanisicak et al., 2016; Fu et al., 2018), a study using another endothelial/endocardial lineage-tracing mouse line, Cdh5-Cre, found that less than 1% of Cdh5 lineage-traced cells (including both endothelial cells and endothelium-derived cardiac fibroblasts) expressed Postn after MI (Kanisicak et al., 2016), suggesting a difference in the transcriptomic regulation of cardiac fibroblasts of different origins. This evidence concerns the gene TCF21 and myocardial infarction.