Absence of Evidence Is Not Evidence of Absence Pitfalls of Cre Knock-Ins in the c-Kit Locus

A recent article by Jeffrey Molkentin's group using mice with Cre/lox knockin in the c-kit locus concludes that, contrary to other reports, c-kit+ cells minimally contribute cardiomyocytes to the heart. We think that the interpretation of the results of the author is problematic because critical data to support their conclusions have not been provided.