Blake Livelyis wishing her "forever sister" Amber Tamblyna very happy birthday.

This Thursday marks the actress' 37th year on this earth and her Sisterhood of the Traveling Pants co-stars are sending

Blake Livelyis wishing her "forever sister" Amber Tamblyna very happy birthday.

This Thursday marks the actress' 37th year on this earth and her Sisterhood of the Traveling Pants co-stars are sending her all the love in the world. On Instagram, Blake shared a cheeky pic of the cast along with a message to her "forever sister," who she forged a strong friendship with on the set of the beloved drama.

Amber re-shared this Instagram Story along with the response: "Love you sis. Truly."

Though Amber, Blake, Alexis Bledel and America Ferrera live in different areas of the country, the actresses continue to be the best of friends, even as the years go by. Amber previously shared that their strong bond can always withstand the test of time. "That's the great thing about really good friendships is you can go a whole year without seeing someone and it's like you're right back in that same moment," she said.