In my field, we're always wanting to see what will happen when DNA is changed in a human pancreatic beta cell. We kind of have a protocol for producing things that look like human pancreatic beta cells from human stem cells, but we're not really sure that they are really going to behave like real human pancreatic beta cells for any particular DNA change, and we have examples of cases where they definitely do not behave the same.
In my field, we're always wanting to see what will happen when DNA is changed in a human pancreatic beta cell. We kind of have a protocol for producing things that look like human pancreatic beta cells from human stem cells, but we're not really sure that they are really going to behave like real human pancreatic beta cells for any particular DNA change, and we have examples of cases where they definitely do not behave the same.
You can't see what's going on in most cases.