Figure 4

Keratinocytes have very low expression of DLL. (A): Next to FACS, Clark et al. [15] used immuno-fluorescence to demonstrate DLL expression in immature keratinocyte-cultures. While the secondary antibody did not give any background staining (LL), there were occasional H265-FITC positive cells (UR), but these always proved to be DAPI negative. In contrast to DLL, immature keratinocytes were reliably stained for the Notch-ligand Jagged-1. (B) For PCR, 4 dilutions (5x-20x-80x-320x) were prepared from cDNA of mKer from 3 donors (A, B, and C), iKer from donor C. Positive controls were prepared from murine TSt-4 cells constitutively expressing DLL-1 or DLL-4. At 35 cycles, DLL4-specific PCR product was only detected in the 5x diluted samples, while mRNA encoding for Jagged-1 was easily amplified in 30 cycles.