Mention of Transgene Insertion into Cell Lines By Transfecting with cDNA - (Jan/20/2015 )

I'm looking into this melanoma cell line (B16) that expresses ovalbumin, but many of the papers that discuss their creation just say that cDNA encoding ovalbumin was transfected into B16 cells.  How would this drive the expression of the transgene (i.e. ovalbumin)?  There's no promoter on cDNA.

I have to read it in context, but it seems like just another example of loose language.

Of course the transgene will need  to be supplied with a promoter, unless it was inserted under an exogenous promoter.

If you transfect "a cDNA" you do it in a vector, the vector has to be mentioned in the paper.

Expression vectors contain already strong (mostly) viral promoters and enhancers (and other features like resistance genes), so you only insert cDNA into it or just buy the vector olready containing complete ORF of the gene you want.