Osteocyte-dependent in vitro myeloproliferation. (A) Schematic representation of cocultures of OEBEs or conditioned media from OEBEs with BM cells in methylcellulose media. (B) Number of myeloid colonies in growth factor-supplemented methylcellulose media (M3434) from coculture of BM cells from control mice with OEBEs from control or OCY-GsαKO mice (n = 4). (C) Number of colonies in growth factor-deficient methylcellulose media (M3231) after coculture of BM cells from control mice with conditioned media from OEBEs from control or OCY-GsαKO mice (n = 4). (D) G-CSF mRNA expression in OEBEs (n = 5). G-CSF in (E) serum (n ≥ 7) and (F) OEBE-conditioned media (n = 6) from control and OCY-GsαKO mice. (G) Number of colonies in growth factor-deficient methylcellulose media (M3231) formed after coculture of BM cells from control mice with conditioned media from OEBEs from control or OCY-GsαKO mice and in the presence or absence of a G-CSF neutralizing antibody (n = 4). Error bars represent mean ± SEM. *P < .05 by t test.