In agreement with the results on Ki67, we didn’t observe any significant uptake of [18F]FLT in L0627 tumors independently from the lesions’ dimension or the treatments’ protocol, possibly due to the lowly proliferative, highly infiltrative nature of CSCs and to the maintenance of Blood Brain Barrier (BBB) integrity in this specific GBM model (43). This evidence concerns the gene MKI67 and glioblastoma.