Receptors involved in the crosstalk between CXCL12 and HER1.

<p>5637 or HeLa cells were cultured alone, or in the presence of 200 ng/mL CXCL12 or 25 ng/mL HB-EGF. After 20 minutes, the cells were collected and evaluated by flow cytometry for the expression of CXCR4 and HER1. (A) Stimulation with CXCL12 led to downregulation of CXCR4 due to its internalization. (B) Stimulation with HB-EGF induced HER1 internalization. In contrast, no changes in the surface expression of HER1 were detected after stimulation with CXCL12. Thus, CXCL12 binding to CXCR4 did not transactivate HER1 in these cells <i>via</i> shedding of HER1 ligands. Representative flow cytometry patterns and the means ±SD of 10 experiments are depicted.