BMP4 and neuroblastoma: Treatment of N2A cells with BMP4, a component of the Bmp pathway that is known to cross-talk with Wnt signalling in neuroblastoma [29], led to a 2.3-fold increase in Tcf7l2 and a subsequent 2.1- and 1.9-fold up-regulation in Paupar and Pax6 expression 72 hours later (Fig 3E).