where in the brain does self-referential processing—the processing of information relevant to ourselves but not others—occur?

cortical midline structures (CMS)

Explanation:

Self-referential processing primarily occurs in the medial prefrontal and the posterior cingulate cortex. Basically, the activities within the cortical midline structures (CMS) such as ventromedial prefrontal cortex and anterior cingulate cortex are associated with the self-referential processing. Self-referential processing involves cognitive thinking that involves linking information from environment to the self. During processing of self- referential information, mPFC i.e Medial prefrontal cortex gets activated

the answer is cell division : )