GRK2 and glioblastoma: Figure 1 shows representative IHC staining with the four markers in GBM and HC. In Figure 2, we present median and Q3–Q1 interquartile range (IQR) values of CS in HC, GBM1 and GBM2. In the control and GBM comparisons, ADRA1D was significantly lower in GBM2 (5 (15–5)) (p = 0.005) and tendentiously lower in GBM1 (15 (25–5)) compared to the HCs (30 (59–13)). In contrast, ADRBK1 was significantly higher in both GBM1 (75 (85–30)) (p = 0.004) and GBM2 (40 (75–20)) (p = 0.012) than in the HCs (9 (25–4)).