A model for glia overmigration when retinal progenitors fitness is compromised by loss of dMyc.

<p>Decreased levels of dMyc in retinal progenitors induce JNK activation and Mmp1 expression in eye disc cells. In a non-autonomous manner glia overmigrates anteriorly to the MF where it displays increased proliferation in response to autonomous pMad activation. JNK activation in the eye disc <i>per se</i> is sufficient to produce Mmp1 and induce glia overmigration but not to stimulate glia proliferation.