6:57 AM PT -- We got Julia as she was released from police custody, saying the sign was a direct message for the honchos at Instagram who have removed her account -- with 5 million followers -- from their platform.
The iconic Hollywood sign got a makeover, and though what went down is technically a crime ... it might be worth the time for supporting a good cause.
Law enforcement sources tell TMZ ... 6 people were arrested for altering the sign to read "Hollyboob" Monday. We're told police were notified of what was going on and tracked the group as they made their way down the hill and busted them.
Our sources say the group -- which we've learned includes model Julia Rose -- told cops they did this to raise breast cancer awareness ... but they will also be cited for trespassing before they're released.
Julia -- who's no stranger to breast-related stunts -- is currently with Hollywood police being processed. We got video of her being led away in cuffs, too.
The timing of the stunt is interesting. As you may know ... Breast Cancer Awareness Month is October, so it seems these folks are several months early.
But on the other hand, February is National Cancer Prevention Month, so like we said ... it's a crime, but also a good reminder to get checked out regularly.