Because EWI‐2 alters the cell surface levels of adhesion proteins and tetraspanins (CD81, CD9, αV integrin), as analyzed by flow cytometry (Fig. 1D), and the EWI‐2 expression is frequently lost in invasive and metastatic cancer cells according to the previous study, we analyzed cell migration and invasion in PC3 NEG and CRISPR/Cas9 KO cells. This evidence concerns the gene CD9 and metastatic malignant neoplasm.