COL1A2 and persistent truncus arteriosus: We subjected Col1a2-CreERT: R26RtdTomato: p53CKO mice to sham injury or TAC 5 days following cessation of tamoxifen injection and examined the injured hearts by immunofluorescence staining of endothelial cell markers, we observed that the expression of p53 was enhanced in tdTomato-labeled fibroblast cells in Col1a2-CreERT: R26RtdTomato mice after TAC, whereas p53 expression levels of tdTomato-labeled cardiac fibroblasts were significantly reduced by approximately 60% on day 7 post-TAC in p53CKO mice (Fig. 4a,b).