Moreover, alpha-smooth muscle actin (α-SMA), normally expressed in differentiating cardiomyocytes, was analysed16,17 40% of myxoma cells expressed α SMA, 67% Plexin A2, 55% Semaphorin 3C, and 30% Calretinin (Supplementary Fig. 1). The gene discussed is PLXNA2; the disease is myxoma.