(a) Western blot analysis of cell lysates isolated from transfected HEK293 cells with pCMV-RET-WT or pCMV-RET-mutants: p.(Arg79Trp), p.(Arg144His), p.(Pro270Leu), p.(Arg694Gln), p.(Ala756Val), p.(Gly533Ser), p.(Tyr1062Cys), p.(Asp489Asn). RET variants p.(Leu56Met) and p.(Tyr1062Phe) were included as controls. (b) Densitometry analysis of p-RET and RET. Values were normalized using GFP and β-actin. (c) Densitometry analysis of p-ERK and RET. Values were normalized using GFP and β-actin. The expression of p-RET or p-ERK is showed as a fold change to RET expression. Three independent experiments were performed (N=3). (*P<0.05, **P<0.01, (−): without GDNF treatment, (+): with GDNF treatment).