CLASP proteins are localized to the basal cortex in lateral epiblast cells. (A and B) When eGFP-CLASP1α (A) or eGFP-CLASP2γ (B) is electroporated into lateral epiblast cells at low concentrations, GFP signals are detected at the basal side. Arrowheads indicate basal localization of CLASP1α (A) and CLASP2γ (B). (C) Endogenous CLASP protein signals detected by cCLASP1 antibody are localized to the basal side. ps, primitive streak. (D and E) Validation of cCLASP1 antibody specificity. In standard MO-electroporated cells (E, yellow arrowheads), basal cCLASP1 antibody signals are not diminished. In CLASP1 MO–electroporated cells, basal cCLASP1 antibody signals are diminished. Yellow arrowheads in D show the normal level of cCLASP1 signals in cells not receiving CLASP1 MO. White arrowheads indicate loss of basal CLASP1 in CLASP1 MO receiving cells. Bars, 20 µm.