FIG. 4.

Identification of upstream DNA sequences of the α-MHC gene required for the repressor activity of the PNR element. Transient-expression analysis of different 5′ progressive deletion mutants of the α-MHC gene with or without the PNR element was carried out by direct injection of DNA into the heart muscle. Expression of pCMV.β-gal in the same heart was used as a reference control. Bars represent the means ± standard errors from four separate injections. Open bars, no PNR element; solid bars, PNR element at the 3′ end of the α-MHC gene; shaded bars, PNR element at the 5′ end of the α-MHC gene fragment.