Fig. 1. P2Y₁R and EGFR expression in non-tumoral epithelial FRT and MDCK cells and in tumoral HeLa cells. Cell extracts analyzed by immunoblot and ECL with polyclonal antibodies against P2Y₁R and the EGFR show readily detectable expression levels of both receptors in HeLa and FRT cells (lanes 1 and 2) but not in MDCK cells (lane 3). The EGFR, but not the P2Y₁R, becomes apparent in MDCK extracts when the film is exposed for a longer time (lane 4). Molecular size markers (in kDa) are indicated on the left.