<p>(A–C) Neuroblasts and progenitor cells of the sensory epithelium had distinct responses to the inhibition of the two independent pathways of pRb phosphorylation. (D1–D2) The explanted otic vesicles were cultured with DMSO, RRD-251 40 µM, or U0126 50 µM for 24 hours and then lysed to detect the level of phosphorylated and unphosphorylated ERK, pRb, and activated Caspase-3. β-actin was used as the loading control. Green arrows indicate the EdU-positive cells, red arrows indicate the Tuj1-positive cells, and the white arrows indicate the Tuj1 and EdU double-positive cells. At least three different experiments were evaluated, and the statistical significance was estimated using one-way ANOVA. * = <i>P</i><0.05 and # = <i>P</i><0.01 compared to controls. Scale bar = 50 µm.</p
