Updated PubMed. For immunoprecipitation to detect the endogenous interaction between VGLL3 and DDX5, cardiac myofibroblasts were fixed with 0.1% PFA and lysed in IP buffer [20 mM HEPES­NaOH (pH 7.5)/1 mM EGTA/1 mM MgCl2/150 mM NaCl /5% glycerol/1% NP­40] containing protease inhibitors (1:100) and phosphatase inhibitors (1:100) at 4 °C for 20 min. The supernatants of cell lysates were incubated for 2 h at 4 °C with SureBeads Protein G (Bio-Rad) coupled with the custom-made rabbit polyclonal anti-VGLL3 antibody, raised against the amino acid sequence of mouse VGLL3 from position 307 to 325. The beads were then washed four times with IP buffer and twice with 50 mM ammonium bicarbonate. Proteins on the beads were digested with 200 ng of Trypsin/Lysyl Endopeptidase mixture, and the digested peptides were reduced, alkylated, acidified, desalted, and dissolved in 0.1% trifluoroacetic acid and 3% ACN. To quantify VGLL3 and DDX5, over four peptides of VGLL3 and DDX5 were measured by PRM, an MS/MS-based targeted quantification method using high-resolution MS. Targeted MS/MS scans were acquired by a time-scheduled inclusion list at a resolution of 70,000, an AGC target of 2e5, an isolation window of 2.0 m/z, a maximum injection time of 1 s, and a normalised collision energy of 27. Time alignment and relative quantification of transitions were performed using Skyline software