Fig. 4. Disappearance of slower mobility isoforms of PML and Sp100 upon heat shock (HS). (A) Western blot of HEp-2 cells exposed to 42°C for various times and probed for PML. (B) Same blot as A after stripping and subsequent probing with anti-Daxx. (C) Same blot as A after stripping and subsequent probing with anti-Sp100. Asterisks indicate the major non-conjugated form of PML and Sp100, respectively; arrows indicate the SUMO-1-conjugated forms of PML and Sp100.