KLF4 and myocardial infarction: Similarly, in vivo assays reported that three days after MI, miR-145 expression decreases as a result of large-scale fibroblast death and the stimulation of an inflammatory response; however, between days 7 and 14 after MI, miR-145 expression gradually increases, promoting the conversion of fibroblasts into functional contractile myofibroblasts by downregulating KLF4 (Krüppel-like factor 4) until 28 days post-MI (Figure 2) [110].