LRM2 is the functional nuclear export signal in c-IAP1. (A) Fluorescence microscopy analysis of HeLa cells transfected for 24 hours with constructs encoding wild-type or mutated GFP-c-IAP1 (nuclei were stained with Hoechst 33342). Leucine residues in LRMs (LRM1^*: Leu250, Leu254, Leu257; LRM2^*: Leu468, Leu472, Leu476, Leu483; LRM3^*: Leu556, Leu558, Leu562, Leu565) were replaced by alanine residues using site-directed mutagenesis. ^*Mutated constructs (magnification ×1000). (B) Western blot analysis of GFP expression in nuclear (N) and cytoplasmic (C) extracts from HeLa cells transfected 24 hours before with indicated constructs.