Figure 4. Dosage compensation fails in many diploid cells relying exclusively on roX1 and H83M2.

(A–A″) Males and females relying entirely on H83M2 showed subnuclear MSL2 staining in all wing imaginal disc cells when both roX1 and roX2 RNAs were present. (B–B″) Many cells lacked dosage compensation if roX1 ⁺ was the only source of roX RNA. (C–C″) MSL2 did not accumulate over the X when both roX1 and roX2 were absent. (D–D″) Nuclear staining of MSL2 was easily detected in the absence of roX RNA after treatment with MG132, a proteasome inhibitor.