Houston rapper Baby Bash vowed to add $5,000 to the reward for information on Guillen in a Facebook announcement on Saturday.
He shared a photo of Guillen's mother and said, "FIND VANESSA!!!!! Anything anybody knows."
SEE RELATED STORY: Extensive search underway for Fort Hood soldier from Houston missing since April
Meanwhile, Mexican-American film actress Salma Hayek posted to her Instagram, with 15 million followers, the following pictures within 24 hours of each other in an effort to bring attention to Guillen's disappearance.
Hayek has really increased the visibility on this case because of her large following on Instagram.
Relatives of Guillen are holding onto hope that she is still alive.
Her sister, Mayra Guillen, said she spoke to Vanessa the day before she reported her missing on April 22.
The founder of lifestyle brand SpoiledLatina also posted to her Instagram, trying to bring the matter to the public's attention.
Fort Hood officials and special agents from the U.S. Army Criminal Investigation Command are asking for the public's help to find Vanessa.
Guillen's family said she was having a problem with someone else at Fort Hood before her disappearance.
A reward of up to $15,000 is now being offered for credible information on her whereabouts.
Vanessa was last seen wearing a black shirt. She is described as being of Hispanic descent, 5 feet 2 inches, and 126 pounds with black hair and brown eyes.
Anyone with information is asked to contact Army CID Special Agents at 254-495-7767 or the Military Police Desk at (254) 287-4001.
The video above is from a previous report.