"be the backbone" is a correct and usable phrase in written English.
It means to provide strong support or stability to something. Example: "Teamwork is the backbone of our project's success."
We are supposed to be the backbone of the intelligentsia".
Information technology will be the backbone of every exchange.
"I pretty quickly realised this could be the backbone for a film.
Researchers consider clinical trials to be the backbone of medical progress.
Traditional airline service will continue to be the backbone of our air transport system.
This principle should be the backbone of scientific engagement with government".
The military that you have joined is, and always will be, the backbone of that leadership.
The SLS is supposed to be the backbone of NASA's deep space aspirations.
The self-employed are supposed to be the backbone of the economy.
As a group, they are meant to be the backbone of the market economy.
If Williams is anything close to what he was, the running game will be the backbone of Saban's offense.
