PAK1 and mitral valve prolapse: Third, we found that the two point mutations in FLNA (G288R and P637Q) that are known to cause degenerative, myxomatous changes in patients that lead to mitral valve prolapse (Sauls et al., 2015) alter the potential of PN to induce the downstream phosphorylation of FLNA at S2152, which normally occurs through a Pak1-dependent events (Figures 6F,G).