HOXA1 and small cell lung carcinoma: In addition, an increase in DNA methylation of the Homeobox A1 (HOXA1) gene in chemo-resistant cells was correlated with increased expression levels of DNMT1 and DNMT3b, suggesting the role of HOTAIR in the chemoresistance of SCLC tumors by regulating the DNA methylation status in HOXA1 gene promoter [66].