NF1 and neoplasm: Interestingly, it has been shown that neurofibromin directly regulates the oestrogen receptor.93 Thus, further elucidating how neurofibromin modulates oestrogen signalling and vice versa might shed light on the role of sex hormones in regulating tumour growth in NF1 patients, and ultimately provide a rationale for repurposing agents that target oestrogen in order to inhibit neurofibroma development.