system
Given the following post, respond as if you're commenting on Reddit:
human
Would an EXTREMIS soldier be affected by Dr. Conners' lizard serum?
gpt
EXTREMIS acts to reverse physical trauma. The lizard serum, whilst also theoretically a healing agent, provides massive physical changes. Whilst the EXTREMIS modifications wouldn't kick in instantly, they would act to reverse the lizard serum's effects. Which would in turn act to reverse EXTREMIS. This would effectively leave the subject in a coma, were it not for the exothermic effects of the former treatment. 

EXTREMIS subjects have been observed to explode if their body rejects the modifications - by introducing the lizard serum, you're forcing a late stage rejection. So yes, your soldier would be affected. Fatally.

Conversely, what would happen if someone already under the effects of the Connors formula were to be injected with EXTREMIS? Assuming the latter took the lizard state to be the norm, you'd end up with A.I.M's treatment's excesses being held in check by the lizard's healing factor (the explosive rejection being less likely when the formula isn't being introduced to regrow a limb in the first place). Then you'd have a lizard creature permanently operating in a warm-blooded state, with strength and speed beyond that of either an EXTREMIS soldier or that reported of Kurt Connors. If Col. Rhodes' mission debrief is to be believed, it may also develop the ability to breathe fire.

In short, you'd have a regenerating dragon with near-impossible speed and strength. If you can fix the psychological issues inherent to Connors' formula, you'd have vastly improved over the original super-soldier serum we experimented with in the '40s.