Analysis of differentiation gene expression by quantitative RT-PCR. The presence of HB-EGF (50 ng/mL) together with differentiation media (AM, adipogenic medium; OM, osteogenic medium) in a 2-week culture is associated with the lack of specific differentiation gene up-regulation. This result is less evident with bFGF (1 ng/mL). FABP4 indicates fatty acid-binding protein 4, adipocyte differentiation; LPL, lipoprotein lipase, adipocyte differentiation; PPARγ, peroxisome proliferative active receptor-γ, adipocyte differentiation; IBSP, integrin-binding sialoprotein II, osteoblast differentiation; and RUNX2, runt-related transcription factor 2, osteoblast differentiation. The expression of each mRNA was calculated by relative quantification using the average of GAPD (glyceraldehyde-3-phosphate dehydrogenase) and ACTB (beta-actin) transcript level as reference (4 duplicates). P < .01 refers to the difference between the arms with differentiation medium (AM or OM) without growth factors and those with either HB-EGF or bFGF, and to the reciprocal comparison of the 2 growth factors. DMEM indicates culture medium without growth factors or differentiation agents. Error bars indicate means ± SD of 4 different experiments.