XBP1 and neoplasm: Transcriptional profiling classified the Ta tumours as luminal (high expression of luminal markers such as GATA3, PPARG, FOXA1 and XBP1 as well as differentiation markers such as UPK1A and KRT20) as well as non-aggressive (high expression of SKAP2, FABP4, MBNL2 and ID1).