Figure S3.

Ionizing radiation–induced influx of FM 1-43 dye is derived from the extracellular space and not by plasma membrane endocytosis. (A) Intracellular staining of FM 1-43 immediately following 10-Gy exposure is not blocked by the endocytosis inhibitor pitstop 2 (20 µM). Data (mean ± SEM) are derived from a minimum of 39 cells per group; ****, P < 0.0001, two-tailed Student’s t test. (B) Removal of extracellular FM 1-43 immediately before irradiation abolishes 10 Gy–induced increase of intracellular dye detection. Data (mean ± SEM) are derived from 15 cells per group.