NOTCH1 and squamous cell carcinoma: The presence of an additional pathogenic mutation in TP53, p.A189P, co-existing on the same allele just two codons downstream from the common p.G187 V mutation (Fig. 3a, bar graph), of two mutations in the related PI3K genes, PIK3CA p.N345K and PIK3CG p.I220T, of a p.M153K mutation of unknown significance in SF3B1 splicing factor gene, known to be mutated in several malignancies, and a likely pathogenic mutation in NOTCH1, p.R1303L, previously described in squamous cell carcinoma [33], indicated much higher variability in this focus compared to the relatively stable brain foci.