Therefore, we studied spheroids from EOC patients’ ascites using a minimal manipulation and surprisingly show here that they are all composed by almost only ovarian cancer cells; these cells display a full epithelial phenotype but also a partial mesenchymal transition consisting of the expression of alpha smooth muscle actin (αSMA) and fibronectin (FN1) secretion, critical for the formation and survival of 3D structures formed by ovarian cancer cells. Here, ACTA1 is linked to ovarian cancer.