MAP2K1 and neoplasm: In some cases, the presence of a major driver mutation coexisting with other variants displaying lower allele frequencies, as in case #23 showing EGFR mutation in 73% of alleles and at lower frequency in TP53 (16%) and MAP2K1 (4%) sustains the hypothesis of tumor molecular heterogeneity and further underlines the demand of a NGS approach to characterize the samples.