Question

Where is presence of dark matter in E=MC^2
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Answer 1

it is presence in the black holes

Answer 2

Dark matter, I propose, does not consist of ordinary positive mass particles. I propose that it is a deficiency of dark energy. All of this is consistent with Einstein’s relativistic energy-mass-momentum equation, special relativity, and the incompatibility of negative energy states with quantum mechanics. There appears to be a source of mass we cannot observe, other than that we don't know much about it. We know it is there from the "extra" gravity coming from what looks like empty space in galaxies. We call this "dark" matter simply because it does not interact with light.