AKR1C1 and small cell lung carcinoma: We identified four protein candidates preferentially expressed in LCNEC compared with SCLC with convincingly low p-values: aldehyde dehydrogenase 1 family member A1 (AL1A1) (p = 6.1 × 10-4), aldo-keto reductase family 1 members C1 (AK1C1) (p = 9.6x10-10) and C3 (AK1C3) (p = 3.9x10-10) and CD44 antigen (p = 0.021).