Unclear whether CellDevelopmentStep from Reactome are biological processes or pathways

[gaurav]

Four Reactome pathways are coming to us classified as a CellDevelopmentStep:

• REACT:R-HSA-9727359 "Keratinocyte of spinosum layer differentiates into keratinocyte of granulosum layer in interfollicular epidermis (Homo sapiens)"
• REACT:R-HSA-9727354 "Transit-amplifying cell of basal layer differentiates into keratinocyte of spinosum layer in interfollicular epidermis (Homo sapiens)"
• REACT:R-HSA-9727355 "Keratinocyte of granulosum layer differentiates into corneocyte of corneum layer in interfollicular epidermis (Homo sapiens)"
• REACT:R-HSA-9725621 "Keratinocyte stem cell differentiates into transit amplifying cell in the basal layer of interfollicular epidermis (Homo sapiens)"

Reactome defines a Cell Development Step as follows: "A Cell Development Step is a ReactionLikeEvent that contains Cell instances as its inputs and outputs. The input attribute represents the cell of origin, and the output attribute represents the destination cell type. Additional Cell Development Step attributes include regulators (molecules promoting or inhibiting the step) and required input components (input cell proteins required for the action of regulators) (Figure 2B)." So their distinctive character is that they are a reaction where cells are both inputs and outputs.

I think that means it should be either a biolink:BiologicalProcess or a biolink:Pathway, but I'm not sure what the distinction between the two are. I'm going to classify them as a BiologicalProcess for now, but if there's a more appropriate class, please let me know!