Interestingly, macropinocytosis-proficient U373-MG cells harbour frameshift indels in the NF1 gene [18], and mutations or deletions in NF1 are typical genetic abnormalities occurring in the transition from the proneural to the mesenchymal subtype of glioblastoma, which has the most aggressive malignant behaviour [38]. This evidence concerns the gene NF1 and glioblastoma.