CXCL1 and breast cancer: Osteocyte regulation of cancer cell behavior has been observed previously, with conditioned media found to alter proliferation, migration, invasion, and extravasation of cancer cells.[13, 14, 15, 16, 18, 19] A recent study has begun the important work of explaining these changes, proposing a potential CXCL1/2‐mediated mechanism through which osteocytes may regulate proliferation of breast cancer cells.[16] However, a general mechanism through which osteocytes control both breast and prostate cancer cell behaviors remains unknown.