NF1 and hereditary pheochromocytoma-paraganglioma: The radiation protocol was used initially by Jacks et al. to increase the frequency of pheochromocytomas in heterozygous Nf1 knockout mice (Jacks et al. 1994) and then in our laboratory to establish the derivative MPC cell lines (Tischler et al. 1995, Powers et al. 2000).