Correct option is B
Explanation-
RhoA Localization and Regulation During Cytokinesis:
A. RhoGEF Ect2 - CORRECT
Ect2 is a RhoA-specific guanine nucleotide exchange factor (GEF). It activates RhoA by facilitating GDP-GTP exchange. Ect2 is essential for RhoA activation at the equatorial cortex during cytokinesis.
B. Aurora B kinase - CORRECT
Aurora B indirectly regulates RhoA by ensuring proper localization of Ect2 and centralspindlin. It’s part of the chromosomal passenger complex (CPC), important in midzone signaling.
C. PLK1 kinase - CORRECT
Polo-like kinase 1 phosphorylates and activates Ect2. It is essential for promoting Ect2 accumulation at the spindle midzone → activates RhoA at the cortex.
D. MKLP1 kinesin - CORRECT
MKLP1 is part of the centralspindlin complex. It is critical for recruiting Ect2 to the spindle midzone → thus indirectly regulates RhoA.
E. ATM and ATR - INCORRECT
ATM and ATR are DNA damage checkpoint kinases. They are not involved in RhoA regulation or cytokinesis under normal conditions.
Correct Answer: Option b (A, B, C, D only)
