KRAS and non-small cell lung carcinoma: More recently, using qRT-PCR Aran and colleagues found that the KRAS4B transcript was two-fold higher than that of KRAS4A in 55 samples of advanced non-small cell lung cancer (NSCLC) but relative to normal lung tissue KRAS4A message was elevated in 42 of 55 patients (Aran et al., 2018).