Reverse proxy with load balancing

[OlympiaLady]

We have a nginx system that does very simple load balancing. Clients contact the proxy server, and are round robined to other systems. I would like to change this setup to a reverse proxy with nginx and ModSecurity. Is it possible to both install nginx integrated with modsecurity and use my same simple load balancing? If not, can I do this with the ModSecurity Apache reverse proxy using mod_proxy_balancer at the same time? The ngnix setup is somthing like:

http {
upstream myapp1 {
server srv1.example.com;
server srv2.example.com;
server srv3.example.com;
}

server {
    listen 80;

    location / {
        proxy_pass http://myapp1;
    }
}

}