A. qPCR analysis for Mfap4 relative to Rpl7 in the indicated groups. (WT and KO sham n=5, WT TAC n=8, KO TAC n=12). (Two-way ANOVA results: WT sham vs TAC p=0.0678; WT vs KO TAC #p=0.00075). B. Immunofluorescence staining of MFAP4 (green) and wheat germ agglutinin (WGA; red) in hearts from the indicated groups. Scale bar, 500 μm. C. Echocardiographic quantification of percentage ejection fraction in WT and MFAP4 KO mice prior to surgery (pre-op) and every two weeks after induction of pressure overload. (WT sham pre-op n=9, KO sham pre-op n=5, WT TAC pre-op n=12, KO TAC pre-op n=10; WT sham 2 weeks n=10, KO sham 2 weeks n=9, WT TAC 2 weeks n=12, KO TAC 2 weeks n=10; WT sham 4 weeks n=5, KO sham 4 weeks n=5, WT TAC 4 weeks n=5, KO TAC 4 weeks n=7). (Two-way ANOVA results for 2 wks time point: WT sham vs TAC *p=0.0112; KO sham vs TAC *p=0.000175; 4 wks time point: WT sham vs TAC *p=0.00042; KO sham vs TAC *p=0.0000012; WT vs KO TAC #p=0.0421). D. Representative picrosirius red – stained cardiac cross-sections from WT and MFAP4 KO mice following 4 weeks of sham or pressure overload (TAC) surgery. Scale bar, 1 mm. E. Quantification of percent fibrosis from picrosirius red - stained cardiac cross-sections in the indicated groups after sham or pressure overload (TAC) surgery. (WT and KO sham n=5, WT TAC n=5, KO TAC n=7). (Two-way ANOVA results: WT sham vs TAC *p=0.0079; KO sham vs TAC *p=0.0060). F. Gravimetric analysis of heart weight to body weight ratio (HW/BW) in the indicated groups 4 weeks after sham or pressure overload (TAC) surgery. (Two-way ANOVA results: WT sham vs TAC *p=0.000017; KO sham vs TAC *p=0.0000086). G. Representative images of WGA-stained cardiac cross-sections of WT or MFAP4 KO mice 4 weeks after sham or pressure overload (TAC) surgery. Scale bar, 50 μm. H. Quantification of cardiomyocyte cross-sectional area based on WGA-stained cardiac cross-sections in the indicated groups. (WT sham n=5, KO sham n=3, WT TAC n=3, KO TAC n=5). (Two-way ANOVA results: WT sham vs TAC p=0.0832; KO sham vs TAC *p=0.00019; WT vs KO TAC #p=0.0420). I. qPCR analysis for hypertrophic gene expression relative to Rpl7 in the indicated groups. (WT and KO sham n=5, WT TAC n=3, KO TAC n=7). (Two-way ANOVA results - Nppa: KO sham vs TAC *p=0.000030; WT vs KO TAC #p=0.0037. - Nppb: WT sham vs TAC *p=0.0201; KO sham vs TAC *p=0.0000098; WT vs KO TAC #p=0.0022. - Myh6: WT sham vs TAC p=0.0560; KO sham vs TAC *p=0.00011. - Myh7: KO sham vs TAC *p=0.000087; WT vs KO TAC p=0.0641. - Acta1: WT sham vs TAC *p=0.0037; KO sham vs TAC *p=0.000055).