Such low toxicity of DDX5 inhibition in normal tissues can be explained by the observation that DDX5 has opposite function in normal cells/tissues versus in cancer cells/tissues: In contrast to the involvement of DDX5 in tumorigenesis, cancer cell proliferation, migration and metastasis [18], DDX5 was recently shown to inhibit smooth muscle cell (SMC) proliferation [134]. Here, DDX5 is linked to cancer.