13 CRA	13-cis retinoic acid
ATRA	all-trans retinoic acid
aSMase	acidic sphingomyelinases
BBB	blood–brain barrier
Bax	BCL2-associated X protein
Bcl-2	B-cell lymphoma
Bid	BH3 interacting domain death agonist
CDK2	cyclin-dependent kinase 2
CDKN1	cyclin-dependent kinase inhibitors
CDKN1A	cyclin-dependent kinase inhibitor 1A
CDKN1B	cyclin-dependent kinase inhibitor 1B
CRYAB	alpha-crystallin B chain
CSCs	cancer stem cells
CYP24	cytochrome P450 family 24
CYP24A1	cytochrome P450 family 24 subfamily A member 1
EGFR	epidermal growth factor receptor
ERK	extracellular signal-regulated kinase
FABP7	fatty acid binding protein 7
FAS	fatty acid synthase
Fas	FS-7-associated surface antigen
FDFT1	farnesyl-diphosphate farnesyltransferase 1
GBM	glioblastoma
GFAP	glial fibrillary acidic protein
hTERT	human telomerase protein reverse transcriptase
IC50	half maximum inhibitory concentration
IDH	isocitrate dehydrogenase
KDM6B	lysine demethylase 6B
MDP1	multidrug resistance protein 1
MEK	mitogen-activated protein kinase
MGMT	O6-methylguanine methyl transferase
MMP-2	metalloproteinase 2
MMP-9	metalloproteinase 9
Nestin	neuroepithelial stem cell protein
nSMase 1	neutral sphingomyelinase 1
NSPc1	nervous system polycomb
Oct4	octamer-binding transcription factor 4
p16INK4a	cyclin-dependent kinase inhibitor 2A
p53	tumor suppressor protein
PARP	Poly (ADP-ribose) polymerase
PERK1/2	activated extracellular signal-regulated kinase ½
PKC	protein kinase C
PRISMA	preferred reporting items for systematic reviews and meta-analyses
PTEN	phosphatase and tensin homolog
RA	retinoic acid
Raf	rapidly accelerated fibrosarcoma
RAR	retinoic acid receptor
RDH16	retinol dehydrogenase 16
RXR	retinoid x receptor
SCL	stem cell-like
Sox2	sex-determining region Y-box 2
TCGA	the cancer genome atlas
TMZ	temozolomide
T3	tocotrienol
TOC	tocopherol
TOS	alpha tocopheryl succinate
TRAIL	TNF-related apoptosis-inducing ligand
VDR	vitamin D receptor