You are part of a research group experimenting with signaling molecules that would tell cancer cells to stop dividing. The cancer cells have inactive receptors on their plasma membrane so you need an alternate method of getting the signals into the cells. What could you use?
A. Plasmodesmata for direct contact.
B. Stimulate the pituitary gland to send the signal as a hormone.
C. Gap junctions for direct contact.
D. Through the synaptic cleft of a neuron.