Fig. 4

Signaling pathway in osteoblasts. The top panel shows representative Western blots of actin, ERK1/2PTyr204, and AKTPSer473 . The cells from a primary culture were grown both in OSC-supplemented medium (20 μg/ml) over a period of 1, 5, 10, and 15 days as well as in medium supplemented with 100 ng/ml IGF-1 for 1 h. Osteoblasts growing over the period of 15 days without OSC-supplementation served as control (c). The bottom panel summarizes the results of three densitometric measurements of AKTSer473 expression (grey column) in relation to the expression level of actin (dotted line). Asterisks indicate significant differences when compared to control (p < 0.001) und hashtags indicate significant differences when compared to day 1 (p < 0.001)