Which of the following is NOT a method used to label a DNA probe?

Sequencing is primarily a technique used to determine the precise order of nucleotides in a DNA molecule rather than a method for labeling probes. While sequencing can provide valuable information about DNA sequences, it doesn't involve the addition of labels to a DNA probe for detection or hybridization purposes.

In contrast, end labeling, nick translation, and random priming are all established methods used specifically to label DNA probes. End labeling typically involves the incorporation of labeled nucleotides at the ends of the DNA fragments. Nick translation involves the enzymatic incorporation of labeled nucleotides while simultaneously removing sections of the DNA, which helps to create probes with a specific label. Random priming results in the synthesis of labeled DNA from a template using short, random primers, allowing for a more extensive coverage of the sequence to be labeled.

These techniques are particularly important in molecular biology for applications like hybridization assays and other forms of genetic analysis, making it clear why sequencing does not fit the category of methods used for labeling DNA probes.