ERBB4 and ovarian carcinoma: Interestingly, the ERL resistant PEO1/ERL cells have increased levels of HER4 (1.5-fold), pNRF2 (2.5-fold), pAkt (1.5-fold) and NRF2-dependent HO-1 (1.5-fold) relative to the parental PEO1 ovarian cancer cells (Figure 5E and F).