BMP4 and intervertebral disk degenerative disorder: In detail, the median concentrations for controls and IDD patients, respectively, were as follows: for BMP2, 32.1 ± 8.9 pg/mL compared with 9.5 ± 2.4 pg/mL (Figure 1B; P < 0.01); for BMP3, 28.7 ± 9.2 pg/mL compared with 14.3 ± 2.6 pg/mL (Figure 1C; P < 0.05); for BMP4, 24.2 ± 6.0 pg/mL compared with 12.5 ± 2.7 pg/mL (Figure 1D; P < 0.01); for BMP5, 24.5 ± 7.1 pg/mL compared with 13.6 ± 3.3 pg/mL (Figure 1E; P < 0.05); and for BMP7, 24.4 ± 5.9 pg/mL compared with 10.1 ± 3.1 pg/mL (Figure 1F; P < 0.01).