ERBB3 and prostate cancer: Moreover, NEDD4 and ErbB3/HER3 protein expression levels are inversely correlated in prostate cancer tissues, suggesting that loss of NEDD4 promotes malignant prostatic cell growth.23 In contrast, inhibition of the nonreceptor tyrosine kinase PKY2 induces ErbB3/HER3 degradation and increases NDRG1 expression in breast cancer cells.