Fig. 6. SHP-2 is required for the survival of proliferating cardiac cells. (A) Xenopus cardiac explants were treated with the SHP-2 inhibitor NSC-87877 beginning at stage 22, 24, 26 or 29 as indicated, cultured to stage 37 and stained with an MHC antibody (red). (B) Representative transverse sections through stage 33, 35, 42 and adult Xenopus hearts with antibodies against MHC (green) or Tmy (green), phosphohistone H3 (red) and DAPI (blue). (C) Representative transverse sections through the cardiac tissue of a DMSO-treated and an explant treated with NSC-87877 beginning at stage 29, and stained with antibodies against phosphohistone H3 (red) and Tmy (green), as assessed at stage 37. (D) Cardiac mitotic index of explants treated beginning at stage 29 with DMSO (blue bar) or NSC-87877 (magenta bar) and assessed at stage 37. Bars represent the mean mitotic index of four explants per condition. Error bars denote the standard deviation. ^*, a statistically significant reduction in mitotic index of NSC-87877-treated explants (P=0.0021). BF, bright field; pH3, phosphohistone H3.