 The mechanism by which the RITS complex induces heterochromatin formation and organization is not well understood.Most studies have focused on the mating-type region in fission yeast, which may not be representative of activities in other genomic regions/organisms.In maintenance of existing heterochromatin regions, RITS forms a complex with siRNAs complementary to the local genes and stably binds local methylated histones, acting co-transcriptionally to degrade any nascent pre-mRNA transcripts that are initiated by RNA polymerase.