Gain-of-function analysis by overexpression of snrk-1 and snrk-1 kinase mutant (snrk-1 KM). (A-C) etsrp⁺ cells in the head (Hd), head to trunk (Hd-Tr), trunk (Tr), trunk to tail (Tr-Ta), tail (Ta), and lateral regions (La) of WT embryos (A), snrk-1 mRNA–injected (B), and snrk-1 KM mRNA–injected (C) embryos. (B) Ectopic induction of etsrp⁺ cells in snrk-1 mRNA–injected embryos. (A,B) Black asterisks in Tr-Ta and Ta panels indicate thicker etsrp-stained region at LPM in panel B compared with panel A. (C) snrk-1 KM mRNA–injected embryos with early migration of angioblasts from the LPM to the midline. (C, Tr-Ta) Inset is higher magnification of prematurely migrating angioblasts at 6 som. (D-F) etsrp⁺ cells in Hd, Tr, and Ta regions at 19 hpf in WT, snrk-1 mRNA–, and KM mRNA–injected embryos. (G) The fold change of etsrp transcript levels in snrk-1 mRNA– and KM mRNA–injected embryos at 6 som by QPCR. (H-K) An in vivo TUNEL apoptosis assay at 24 hpf in WT, MO1-, MO2-, and snrk-1 mRNA–injected embryos. (J,K) Arrows indicate apoptotic cells. (L) The mean number of apoptotic nuclei (x-axis) in the vessel region in each sample (y-axis: WT, n = 10; MO1, n = 14; MO2, n = 18; snrk-1 mRNA, n = 11), with the error bars representing SD. Paired t test: *P < .05 between WT and MO1; **P < .05 between WT and MO2; ***P < .005 between WT and snrk-1 mRNA samples.