Further compaction leads to transcriptionally inactive heterochromatin. The variant functions with transcriptionally active domains. By intercalation, doxorubicin can also induce histone eviction from transcriptionally active chromatin. MeCP2 has been found to associate most strongly with transcriptionally inactive chromomere domains. The lateral loops are areas where the chromosomes are transcriptionally active. In mammalian cells, DNA methylation is the primary marker of transcriptionally silenced regions. In the Golgi, SREBF1 is cleaved and released as a transcriptionally active mature protein. For instance, acetylation of H4K12 has been associated with condensed and transcriptionally inactive chromatin. Relaxed, transcriptionally active DNA is referred to as euchromatin. Presumably, PcG complexes are responsible for transcriptionally repressing differentiation and development-promoting genes. The resultant tightly packed chromatin is transcriptionally inactive. While these cofactors are present, TR binds HREs in a transcriptionally inactive state. Two separate, site-specific proteolytic cleavages are necessary for release of the transcriptionally active amino-terminal domain. However, transcriptionally active rDNA resides inside of the nucleolus itself. TR/RXR heterodimers are the most transcriptionally active form of TR.