p53

(Grammatically speaking, it is ?)

(1) in this case p53 = in this case we refer to p53 gene?

(2)
Proteins = the molecules?

(Grammatically speaking, it is ?)

Context:

When a gene is transcribed or "read," in this case p53, a copy of the gene is made in RNA. In a normal cell, that p53 RNA carries the instructions to make p53 proteins, which in turn carry out the tumour suppressor function in cells.
"MicroRNAs act to control the production of proteins -- the molecules that do the work in cells," explained Swarbrick.

More:

http://www.sciencedaily.com/releases/2010/09/100928092843.htm

I saw the thread title in the list, and thought it was gonna be about a World War II fighter i had never heard of.