Gel electrophoretic analysis of ethidium bromide–stained RT-PCR products generated from mRNAs encoding RARα1-PML (left panel) or RARα2-PML (right panel) from L-form, V-form, and S-form PML-RARα mRNA type cases, including one atypical S-form case (Sv). M is Hae III-digested φX174 DNA marker; 0 is 0 RNA control.