RANKL is produced by all except

RANKL is produced by all except?
A. Osteocytes
B. Osteoclasts
C. Activated T cells
D. Bone marrow stromal cells

Correct answer : B. Osteoclasts

RANKL (TNFSF11) – Protein structure rendering

RANKL (Receptor Activator of Nuclear factor Kappa B Ligand), also known as Tumor Necrosis Factor ligand Super Family member 11 (TNFSF11) is produced by osteocytes, activated T cells and bone marrow stromal cells.
RANKL acts on the RANK receptor present on osteoclasts and their precursors.
It promotes maturation of osteoclast precursors into mature osteoclasts.

Ref: Davidson’s Principles and Practice of Medicine, 22nd Edition, p1062
Image credits: Author: Emw. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. http://en.wikipedia.org/wiki/File:Protein_TNFSF11_PDB_1s55.png