be the backbone(the backbone of something the most important part of an organization or group of people: Farmers are the backbone of this community. LDOCE. the most important part of something, providing support for everything else Farming and cattle-raising are the backbone of the country's economy. CALD Alexander Demidov)
comprise the backbone(of: Family caregivers comprise the backbone of long-term-care provision in the United States, yet little is known about how the composition and experience of family caregiving has changed over time.aldrignedigen)
