GFAP and central nervous system cancer: That is,2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$ D(t)={\displaystyle \int u(x){p}_{GFAP}\left(x,t\right)dx}, $$\end{document}Dt=∫uxpGFAPxtdx,where pGFAP(x, t) is the probability distribution function (PDF) describing the concentration (x) of GFAP across a population, and u(x) is a microscopic indictor function describing the effect of the drug on the differentiation of glioma cells at a given GFAP level.