Fig. 8. In transfected parietal cells, expression HA-tagged lasp-1, forskolin stimulation also induces the recruitment of this protein to the canalicular region. However, mutation of the two major cAMP-dependent phosphorylation sites, S⁹⁹ and S¹⁴⁶, to alanines appears to block this cAMP-dependent process and may also inhibit the acid secretory response. Panels a,c,e,g show signals derived from HA-tagged lasp-1 construct (a,c) and for HA-tagged double S⁹⁹/S¹⁴⁶ (RRDA/RGFA) mutants (e,g). Corresponding F-actin signals in the same cells are shown in panels on the right. Arrows indicate location of expended intracellular canaliculi; arrowheads indicate intracellular canaliculi in non-transfected cells. Note non-transfected cell in panel h (actin signal only)is clearly stimulated by forskolin addition but the transfected cell is not. Data representative of six independent experiments. Bars, 10 µM.