However, the lack of cooperation between Notch1 gene loss and expression of Pik3caE545K does not appear to affect the ability of Notch1 deletion to skew tumors towards a squamous fate, revealing a separation between the ability of alterations in the Wnt/Notch signaling axis to promote transformation from their ability to effect tumor histology. The gene discussed is NOTCH1; the disease is neoplasm.