In higher eukaryotes, 28S rRNA contains 12 conserved but variable divergent domains (D1-D12), originating from evolutionary large-scale length and diversity expansions (Michot et al., 1984) . Although the functions of D domains are not clearly understood, D2 and D8 have higher divergency rates than other domains (Houge et al., 1995) . Mouse 28S rRNA cleavage sites have been mapped to be within D2 (approximately 400-1140 nts) and/or D8 domains (approximately 2700-3280 nts) (Houge et al., 1993; Houge et al., 1995; Houge and Doskeland, 1996; Naito et al., 2009) . Apoptosisassociated cleavage pathways were previously reported to target D2 and D8 followed by secondary cleavage in other domains. As demonstrated here, DON-induced rRNA cleavage fragments (b-f) were from the D8 region, whereas two other cleavage sites (a and e) were within D10 (approximately 3785-3822 nts) (Michot et al., 1984) rather than canonical D2. It might be speculated that DON treatment rendered D8 and D10 accessible to constitutive and/or inducible RNases, whereas D2 did not.