PML and acute promyelocytic leukemia: Breakpoint analysis on a limited number of secondary or therapy-induced APL (t-APL) cases reveals the presence of an 8-base pair “hotspot” region in PML intron 6 in patients receiving mitoxantrone, while the site preferences for epirubicin-induced APL is less clear-cut but different from the mitoxantrone-associated hotspot [5–7].