HIF1A and neuroblastoma: Since stabilization of HIF-1α protein has been shown to decrease c-RET mRNA in a human lung cell line38 and to decrease c-RET protein in a human neuroblastoma cell line30, we hypothesized that the mechanism of Mn-mediated decrease of c-Ret protein occurs at the transcriptional level mediated by stabilization of Hif-1α protein in SGNs (Figure S2).