Fig. 4. Effect of RA on apoptosis in P388D1 cells. Stably transformed P388D1 cells overexpressing the M6P/IGF2R (C and D) and control P388D1 cells (receptor negative; A and B) were treated with (B and D) or without (A and C) 1 µM RA for 48 h. Apoptotic cells were detected by TUNEL assay using the in situ apoptosis detection system, Fluorescein (Promega). Bright spots, (green fluorescence; D) fragmented DNA in apo-ptotic cells.