REAGENT or RESOURCE	SOURCE	IDENTIFIER
Chemicals, Peptides, and Recombinant Proteins
Probenecid	Sigma-Aldrich	P8761
Calcein-AM	ThermoFisher	C3100MP
D-mannitol	Sigma-Aldrich	M4125
DMEM HEPES formulation	Sigma-Aldrich	D1152
Other
Clear-bottomed, black-walled, flat, sterile, cell culture treated microplates	Corning	3904
Fluorescence plate reader	BMG Labtech	FLUOstar Omega
Freezing point depression osmometer	Löser	Micro-Digital i-Osmometer Basic 7i
Coulter counter	Beckman Coulter	Z1
0.2 μm syringe filter	Any supplier	N/A
Experimental Models: Cell Lines
Madin-Darby canine kidney (MDCK) cells	ATCC	CRL-2936
HEK293 cells	ATCC	CRL-1573
Primary astrocytes (rat)	ThermoFisher	N7745100
Primary astrocytes (human)	ScienCell	1800
Breast cancer cell lines (MDA-MB-231)	ATCC	HTB-26
Breast cancer cell lines (MCF7)	ATCC	HTB-22