Dr. Youn left an interesting comment on this site earlier explaining that injecting lips with Restylane or collagen is increasingly common these days especially for certain professions;

"...it is EXTREMELY common for models and actresses to have collagen or restylane injected into their lips. Because it doesn't take much time, leaves no scars, and can make some major changes, many celebrities get their lips augmented on a regular basis."

Photo by: Lady Kubricka