ERBB2 and breast cancer: The permeation across barriers is followed by ex vivo fluorescence microscopy at 534–558 nm excitation wavelength and 560–640 nm emission wavelength [17] of sliced tissue after IV injection and in vivo fluorescence labeled permeation of 14-week-old BALB/C and C57BL/6J (BL/6) mice (Charles River Laboratories, Wilmington, MA, USA) for normal brain BBB experiments [17], imaging and fluorescence guided resection experiments [34], and preclinical HER2-positive breast cancer treatment [23].