TRAF6 and ovarian cancer: As presented in Fig. 4A–C, shTRAF4 knockdown SK-OV-3 cells, shTRAF5 knockdown MeWo cells, and shTRAF6 knockdown MeWo cells formed fewer colonies than the control cells without the retinoic acid treatment, indicating that TRAF4, TRAF5, or TRAF6 knockdown alone has successfully suppressed the growth of human ovarian cancer or human melanoma cells.