GPR17 and glioblastoma: Stringer et al. (2019) cultured low-passage primary patient GBM cell lines, such as MMK1, RN1, and JK2, from different age groups, and their demographic features are represented in Figure 6A. Strikingly, microarray analysis revealed the expression variation of GPR17, where MMK1 was implicated as having the highest level of expression followed by RN1 and JK2.