S100A13 and central nervous system cancer: To examine whether ANXA2 associates with S100A13, the cargo protein mediating stress-induced non-classical release under serum-free conditions [11,14], we first performed a pull-down assay using the lysates of C6 glioma cells expressing Strep-tagII-S100A13 in the absence or presence of 100 μM of Ca2+.