Final answer:
Kuper's four panels likely illustrate a sequential and symbolic part of the narrative in which Gregor's condition becomes apparent to others, much like mythological or commemorative panels that depict significant stories or events.
Step-by-step explanation:
As Gregor stands up and unlocks the door, Kuper uses four panels to show a sequence of events that are both significant to the story and rich in symbolism. These mythological panels often serve to depict key scenes just like historic processional friezes or the intricate bronze doors cast by Bernward of Hildesheim commemorate the fall and redemption of mankind.
Typically, such artistic panels serve to provide narrative, thematic, or symbolic details that enhance the story's depth or the understanding of a character's journey or challenges. Similar to the abstract action within frames mentioned in the background of the quote, Kuper's panels would likely distill the essence of the moment Gregor's metamorphosis becomes evident to others.