Cardiomyocyte and cardiac fibroblast cell types specific knockout mice demonstrate reduced doxorubicin-induced cardiac injury. LV FS was assessed in (A) Par1^fl/fl;Mlc2v^cre+ cardiomyocyte-specific Par1 knockout mice and Par1^fl/fl wild-type controls (n = 7-10/group per timepoint) or (B) Par1^fl/fl;Tcf21^creERT2+ cardiac fibroblast specific Par1 knockout mice and Par1^fl/fl wild-type controls (n = 5-7/group per timepoint) at baseline and on day 5 in the acute model of doxorubicin-induced cardiac injury by conscious echocardiography. #P < .05 vs baseline of the respective genotype; ∗∗P < .01; 2-way ANOVA with post hoc Holm-Sidak tests. Data are represented as individual values with the mean and SEM.