From all my limited research over the past few weeks, this is what I've gathered.
IGF attaches to receptor sites that make cells grow. I don't know what cells have receptors, but seems like all cells have receptror, which is why too much will give you GH gut, and also why IGF is commonly pinned bilaterally in the trained muscles. The injected stuff will atach to local receptors, and the rest will circulate. LR3 makes it not break down immediately when it hits the bloodstream, alowing it to travel and attach to other receptors when/if it gets into the bloodstream.
Fat cells are still cells, and I hope they don't have IGF receptors... get what I'm saying?
It's easy to pin IM with IGF. a slin pin in your quads, biceps, delts, tris, lats, etc... so why subQ?