“…6F,L and data not shown, n>70 for each marker) three transcription factors required for PMC specification (Croce et al, 2001b;Ettensohn et al, 2003;Kurokawa et al, 1999), were unaffected by FGFA morpholinos, suggesting that FGFA signaling participates in regulating PMC differentiation, although not their specification. We then examined the expression of gene markers in the ectoderm, such as otp (Cavalieri et al, 2003; Di 359 RESEARCH ARTICLE FGF signaling in the sea urchin embryo Bernardo et al, 1999), fgfA, pax2/5/8 and pea3, in the FGF morphants. Expression of the homeobox gene otp, which has been implicated previously in skeletogenesis, was largely unaffected (data not shown, n>40) following downregulation of FGFA.…”