FIGURE 3.

Rspo1 stimulates β-cell proliferation. A, MIN6 β-cells were treated with either medium alone (control), EX4, Wnt3a or increasing doses of Rspo1 overnight, and their proliferation index was determined by [³H]thymidine incorporation assay (n = 14–33). B, dispersed murine islet cells were treated with medium alone (control), EX4 or Rspo1for 48 h, and BrdU was added for the last 24 h. Cells were then fixed and co-stained for insulin and BrdU. Proliferative index was determined as the number of BrdU- and insulin-positive cells over total insulin-positive cells, and data are presented as fold of control (n = 4). *, p < 0.05; **, p < 0.01.