DLX5 promotes proliferation of lung cancer cells by regulating the expression of MYC. A, real time RT-PCR analyses of -fold change of DLX5 and MYC mRNA levels in NCI-H322M, NCI-H520, or NCI-H23 lung cancer cells transfected with siRNA against DLX5 (siDLX5; Invitrogen Oligo ID, HSS102810) or non-targeting siRNA (siCON) for 16 h or 24 h. The DLX5 and MYC mRNA levels were normalized against the respective DLX5 and MYC mRNA levels observed in cells transfected with control non-targeting siRNA. B, the same number of cells were transfected with buffer (Normal), non-targeting siRNA (siCON), siRNA1 against DLX5 (siDLX5-1; Invitrogen Oligo ID, HSS102808), or siRNA2 against DLX5 (siDLX5-2; Invitrogen oligo ID, HSS102810) and counted 48 h after transfection. C, cell numbers counted at 48 h in NCI-H322M cells transfected with buffer (NCI-H322M), non-targeting siRNA (siCONTROL), siRNA1 against DLX5 (siDLX5-1), siRNA2 against DLX5 (siDLX5-2), siRNA1 against DLX5 + pcDNA3-MYC (siDLX5-1 + MYC), or siRNA2 against DLX5 + pcDNA3-MYC (siDLX5-2 + MYC). D, expression of DLX5, CASPASE 3, and β-ACTIN in NCI-H322M cells transfected with buffer (Normal), non-targeting siRNA (siCON), siRNA1 against DLX5 (siDLX5-1), or siRNA2 against DLX5 (siDLX5-2). The arrow points to the bands representing the cleaved form of active CASPASE 3.