Identification of the actin nucleators in mouse and rat salivary glands. (A) Acinar cells were examined for actin nucleator mRNA expression. Salivary glands of the acinar-specific Mist1-inducible/membrane reporter mTom/mGFP mouse were transfected with an AAV9 Cre-vector by injection into the Wharton duct. Cells were sorted by their fluorescence (+GFP, −GFP) to identify acinar cells (+GFP) and actin nucleator transcript levels were measured using qPCR. (B and C) WT mice were either injected with 0.01 mg/kg ISOP (B) or left untreated (C). Salivary glands were processed for cryosectioning and indirect immunofluorescence and labeled with Alexa 647 phalloidin (green) and antibodies raised against phospho-Arp2, ARPC2, N-WASP or cortactin (Alexa Fluor-488 goat anti-rabbit, magenta). Insets show individual granules (B) or the APM (C). Bar, 3 µm; 1 µm insets. (D) Wistar rats were either injected with 0.025 mg/kg ISOP or left untreated (CTRL). Salivary glands were processed for cryosectioning and indirect immunofluorescence and labeled with Alexa 647 phalloidin (green) and antibodies raised against mDia1 or ARPC2 (Alexa Fluor-488 goat anti-rabbit, magenta). Insets show individual granules (ISOP) or the APM (CTRL). Bar, 3 µm; 1 µm insets.