HOXD4 and neoplasm: As shown in Table 2, compared with normal ovarian tissues, HOXD3 was significantly lower expressed in OC tumor tissues (fold change = 0.331, P = 0.026), HOXD4 was significantly lower expressed in OC tumor tissues (fold change = 0.155, P < 0.001), HOXD8 was significantly lower expressed in OC tumor tissues (fold change = 0.280, P < 0.001), HOXD9 was significantly lower expressed in OC tumor tissues (fold change = 0.373, P = 0.009), and HOXD12 was significantly higher expressed in OC tumor tissues (fold change = 6.720, P < 0.001).