Recent studies of the hedgehog signalling pathway have shown it to be a key regulator of animal development across organisms from flies to humans.

The detective recognized the gang signal and radioed for backup.

When introducing a source, always include a clear signal phrase to show whether you are quoting directly or paraphrasing.

Good writers use signal phrases to introduce sources and clarify attribution in their essays.

The ship's captain waited for the exact time signal before setting the chronometers.

Please wait at the crosswalk until the traffic signal turns green.

During the field test, the signal-to-noise at the receiver was only 8 dB, which meant the ratio comparing signal power to noise power was insufficient for reliable communication.

The engineer sampled the digital signal at regular intervals to convert it into a binary stream for processing.

Engineers designed filters to reduce noise in analog signals before conversion.

Engineers analyzed the digital signals to improve network reliability.