Fig. 7. Effect of co-transfection of MyoD with Runx2/Cbfa1 on ALP activity. (A) C3H10T1/2 cells were transiently transfected with MyoD- or Runx2/Cbfa1-expression vectors alone or in combination. Co-transfection with ß-Gal-expression vector allowed identification of transfected cells. Cultures were double-stained for ß-Gal and ALP activity after a 3-day incubation in differentiation media. MyoD and Runx2/Cbfa1 transfected cells tended to show more double-stained cells than cells transfected with Runx2/Cbfa1 alone (arrow in A); however, the difference did not reach statistical significance. (B) Immunohistochemical analyses of Runx2/Cbfa1 expression in C3H10T1/2 cells at day 0 and after 3 days in low mitogen media containing 400 ng/ml of BMP-7, revealed protein expression in BMP-7 treated cultures.