According to the documentation this should work:
apex.region("empIG").widget().interactiveGrid("getActions").invoke("save");
However, this throws an “undefined” error.
The save action is indeed not available:
apex.region("empIG").widget().interactiveGrid("getActions");
This is a part of the actions list:
I do not have an older version of APEX readily available, but I'm quite sure it used to work. An app upgraded from an older version used this code, that doesn't work anymore:
apex.region("empIG").call("getActions").invoke("save");