IGF1 and Langer mesomelic dysplasia: Recent studies have shown how cancer cells colonize the unique environment of the leptomeningeal space,4,5 and we have previously performed unbiased omics-based analyses of CSF from patients with LMD.2 We found that the CSF was enriched with proteins involved in innate immunity, protease-mediated damage, and insulin-like growth factor– (IGF–) related signaling.