TF and glioblastoma: In this context, receptors and transporters overexpressed on the BBB, such as transferrin (Tf) [25], insulin [26], low-density lipoprotein [27], lactoferrin (Lf) [28], nicotinic receptors [29], and glucose [30] and choline transporters [31], have been extensively studied and exploited to improve the targeting and crossing of the BBB by NPs, with the aim of GBM treatment; however, the recent literature on BBB-permeable systems evidences how targeting single receptors and transporters has limited efficacy.