Next, we used RET-transgenic mice carrying constitutively activated RET (RFP-RET) (RET-Tg mice) of line 242, in which no tumor develops without exception20, 26, 32, and litter WT mice in order to determine whether Mn-mediated hearing loss involves impairment of c-Ret in SGNs in vivo. Here, RET is linked to neoplasm.