Our results showed that DKK4 knockdown significantly decreased the incidence of invasion in ovarian cancer cells (SKOV-3: control siRNA (177.97 ± 29.59) vs. DKK4 siRNA (49.43 ± 23.57), p < 0.0001; HO-8910: control siRNA (167.63 ± 11.91) vs. DKK4 siRNA (53.23 ± 4.41), p < 0.0001) (Fig. 3c and d). This evidence concerns the gene DKK4 and ovarian cancer.