EREG and cancer: Gliomas exhibit genetic heterogeneity at the intratumoral level, and proteins secreted from cancer cells potentially affect adjacent cells.24,25 EREG, a secreted protein, has been reported to be involved in the paracrine regulation of tumor progression.26,27 Accordingly, we assessed whether EREG secretion by U87MG cells through a mechanism mediated by the Rab27b pathway after IR treatment exerts paracrine effects on different types of glioma cells, particularly the low-grade, radiation-sensitive H4 cell line.